TY - CONF
A1 - Fink, Friedrich
T1 - From Bench to Mini – Identification of technical Lignins with NIR
N2 - One of the most underutilized biological materials on our planet is lignin. It is the second most abundant biopolymer after cellulose. On an industrial scale, it mainly accumulates as a by-product in the pulp and paper industry. However, the utilization of technical lignins faces several challenges, including their complex and heterogeneous structure, which makes them difficult to process and limits their application. Additionally, the feedstock origin is a limiting factor. Classification according to the biomass origin is important for quality assurance and predictability of potential applications.
In this study, technical lignins were analyzed using a near-infrared (NIR) spectrometer. Different models were developed to classify these lignins, enabling rapid and reliable identification of their biomass sources, including softwoods, hardwoods, straw, and grasses. Various machine learning algorithms such as Support Vector Machines (SVM), Gaussian Process Classification (GPC), Gaussian Naive Bayes (GNB), and Decision Tree Classification (DTC) were compared based on different spectral preprocessing techniques and dimensionality reduction tools. The efficacy of the method was further tested using combined spectra from small handheld and compact spectrometers.
T2 - ESOPS 2024
CY - Berlin, Germany
DA - 09.09.2024
KW - NIR
KW - Lignin
PY - 2024
AN - OPUS4-62275
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Martynenko, Irina
A1 - Litvin, A.P.
A1 - Purcell-Milton, F.
A1 - Baranov, A. V.
A1 - Fedorov, A.V.
A1 - Gun´ko, Y.K.
T1 - Application of semiconductor quantum dots in bioimaging and biosensing
N2 - In this review we present new concepts and recent progress in the application of semiconductur quantum dots (QD) as labels in two important areas of biology, bioimaging and biosensing. We analyze the biologically relevant properties of QDs focusing on the following topics: QD surface treatment and stability labeling of cellular structures and receptors with QDs, incorporation of QDs in living cells, cytotoxicity of QDs and influence of the biolocical environment on the biological and optical properties of QDs. Initially, we consider utilization of QDs as agants in high-resolution bioimaging techniques that can provide information at the molecular levels. The deverse range of modern live-cell QD-based imaging techniques with resolution far beyond the diffraction limit of light is examined. In each technique, we discuss the pros and cons of QD use and deliberate how QDs can be further engineered to facilitate their application in the respective imaging techniques and to produce significant improvements in resolution. Then we review QD-based point-of-care bioassays, bioprobes, and biosensors designed in different formats ranging from analytic biochemistry assays and ELISA, to novel point-of-care smartphone integrated QD-based biotests. Here, a wide range of QD-based fluorescence bioassays with optical transduction, electrochemiluminescence and photoelectrochemical assays are discussedc. Finally, this review provides an analysis of the prospects of application of QDs in selected important Areas of biology.
KW - Fluorescence
KW - Semiconductor quantum dot
KW - Imaging
KW - Quantification
KW - Nanoparticle
KW - NIR
KW - IR
KW - Quantum yield
KW - Method
KW - Microscopy
KW - Assay
KW - Bioconjugate
PY - 2017
DO - https://doi.org/10.1039/c7tb01425b
VL - 5
IS - 33
SP - 6701
EP - 6727
PB - Royal Society of Chemistry
AN - OPUS4-43027
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Altenburg, Simon
A1 - Straße, Anne
A1 - Gumenyuk, Andrey
A1 - Maierhofer, Christiane
T1 - In-situ monitoring of a laser metal deposition (LMD) process: comparison of MWIR, SWIR and high-speed NIR thermography
N2 - Additive manufacturing offers a range of novel applications. However, the manufacturing process is complex and the production of almost defect-free parts with high reliability and durability is still a challenge. Thermography is a valuable tool for process surveillance, especially in metal additive manufacturing processes. The high process temperatures allow one to use cameras usually operating in the visible spectral range. Here, we compare the results of measurements during the manufacturing process of a commercial laser metal deposition setup using a mid wavelength infrared camera with those from a short wavelength infrared camera and those from a visual spectrum high-speed camera with band pass filter in the near infrared range.
KW - Additive Manufacturing
KW - Process monitoring
KW - Thermography
KW - LMD
KW - Metal
KW - MWIR
KW - SWIR
KW - NIR
PY - 2020
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-516318
DO - https://doi.org/10.1080/17686733.2020.1829889
VL - 19
IS - 2
SP - 97
EP - 114
PB - Taylor & Francis Group
CY - London, UK
AN - OPUS4-51631
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Grauel, Bettina
A1 - Würth, Christian
A1 - Homann, C.
A1 - Krukewitt, Lisa
A1 - Andresen, Elina
A1 - Roik, Janina
A1 - Recknagel, Sebastian
A1 - Haase, M.
A1 - Resch-Genger, Ute
T1 - Volume and surface effects on two-photonic and three-photonic processes in dry co-doped upconversion nanocrystals
N2 - Despite considerable advances in synthesizing high-quality core/shell upconversion (UC) nanocrystals (NC; UCNC) and UCNC photophysics, the application of near-infrared (NIR)-excitable lanthanide-doped UCNC in the life and material sciences is still hampered by the relatively low upconversion luminescence (UCL) of UCNC of small size or thin protecting shell. To obtain deeper insights into energy transfer and surface quenching processes involving Yb3+ and Er3+ ions, we examined energy loss processes in differently sized solid core NaYF4 nanocrystals doped with either Yb3+ (YbNC; 20% Yb3+) or Er3+ (ErNC; 2% Er3+) and co-doped with Yb3+ and Er3+ (YbErNC; 20% Yb3+ and 2% Er3+) without a surface protection shell and coated with a thin and a thick NaYF4 shell in comparison to single and co-doped bulk materials. Luminescence studies at 375 nm excitation demonstrate backenergy transfer (BET) from the 4G11/2 state of Er3+ to the 2F5/2 state of Yb3+, through which the red Er3+ 4F9/2 state is efficiently populated. Excitation power density (P)-dependent steady state and time-resolved photoluminescence measurements at different excitation and emission wavelengths enable to separate surface-related and volume-related effects for two-photonic and threephotonic processes involved in UCL and indicate a different influence of surface passivation on the green and red Er3+ emission.
The intensity and lifetime of the latter respond particularly to an increase in volume of the active UCNC core. We provide a threedimensional random walk model to describe these effects that can be used in the future to predict the UCL behavior of UCNC.
KW - Nano
KW - Nanomaterial
KW - Upconversion
KW - Nanoparticle
KW - Lanthanide
KW - Photoluminescence
KW - Quantum yield
KW - Pphotophysics
KW - Lifetime
KW - Sensor
KW - Excitation
KW - Power density
KW - Single particle
KW - Brightness
KW - NIR
KW - Mechanism
KW - Modeling
KW - Simulation
KW - Energy transfer
PY - 2022
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-535317
DO - https://doi.org/10.1007/s12274-021-3727-y
SN - 1998-0124
VL - 15
IS - 3
SP - 2362
EP - 2373
PB - Springer
AN - OPUS4-53531
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Ahiboz, D.
A1 - Andresen, Elina
A1 - Manley, P.
A1 - Resch-Genger, Ute
A1 - Würth, Christian
A1 - Becker, C.
T1 - Enhanced photon upconversion using erbium-doped nanoparticles interacting with silicon metasurfaces
N2 - Photon upconversion (UC) using trivalent erbium (Er+3) doped crystals is a promising concept to harness near infrared photons of the solar spectrum which cannot be directly absorbed by silicon solar cells. However, their UC efficiency at low-intensity 1 sun illumination is not relevant on device level so far. Exploiting giant near-field enhancement effects on metasurfaces is an appealing approach to enable efficient UC at low irradiance conditions. Here, we report on more than 1000-fold enhanced photon UC of NaYF4:Er+3 nanoparticles interacting with the near-fields supported by a silicon metasurface under 1550 nm excitation.
T2 - 48th Photovoltaic Specialists Conference (PVSC)
CY - Online meeting
DA - 20.06.2021
KW - Nano
KW - Nanomaterial
KW - Upconversion nanoparticle
KW - Lanthanide
KW - Photoluminescence
KW - Quantum yield
KW - Photophysics
KW - Lifetime
KW - Sensor
KW - Excitation power density
KW - Brightness
KW - NIR
KW - Mechanism
KW - Modeling
KW - Simulation
KW - Energy transfer
KW - Photonic crystal
KW - Enhancement strategy
PY - 2021
DO - https://doi.org/10.1109/pvsc43889.2021.9518495
SP - 1
EP - 3
PB - IEEE
CY - Berlin
AN - OPUS4-53786
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Resch-Genger, Ute
T1 - Quantitation of luminescent properties of Yb and Ho co-doped NaYF4 colloidal nanoparticles - novel active-core-active-shell materials and novel characterization methods
N2 - At the core of luminescence color and lifetime tuning of rare earth doped upconverting nanoparticles (UCNPs) is the understanding of the impact of the particle architecture for commonly used sensitizer (S) and activator (A) ions. In this respect, we present here a series of core@shell NaYF4 UCNPs doped with Yb3+ and Ho3+ ions, where the same dopant concentrations were distributed in different particle architectures following the scheme: YbHo core and YbHo@..., …@YbHo, Yb@Ho, Ho@Yb, YbHo@Yb, and Yb@YbHo core-shell NPs. As revealed by quantitative steady state and time-resolved luminescence studies, the relative spatial distribution of the A and S ions in the UCNPs and their protection from surface quenching has critical impact on their luminescent characteristics. Interestingly, although the increased amount of Yb3+ ions boosts UCNP performance by increasing the absorption, the Yb3+ ions can also dissipate the energy stored in the material through energy migration to surface, thereby reducing the overall energy transfer efficiency to the activator ions.
T2 - COST Workshop
CY - Aveiro, Portugal
DA - 30.06.2017
KW - Upconversion
KW - Nanoparticle
KW - Flourescence
KW - Core-shell architecture
KW - NIR
KW - Absolute flourometry
KW - Integrating sphere spectroscopy
KW - Ho(III)
KW - Yb(III)
PY - 2017
AN - OPUS4-41161
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Bandi, V.G.
A1 - Luciano, M.P.
A1 - Saccomano, M.
A1 - Patel, N.L.
A1 - Bischof, Th. S.
A1 - Lingg, J.G.P.
A1 - Tsrunchev, P.T.
A1 - Nix, M.N.
A1 - Ruehle, Bastian
A1 - Sanders, C.
A1 - Riffle, L.
A1 - Robinson, C.M.
A1 - Difilippantonio, S.
A1 - Kalen, J.D.
A1 - Resch-Genger, Ute
A1 - Ivanic, J.
A1 - Bruns, O.T.
A1 - Schnermann, M.
T1 - Targeted multicolor in vivo imaging over 1,000 nm enabled by nonamethine cyanines
N2 - Recent progress has shown that using wavelengths between 1,000 and 2,000 nm, referred to as the shortwave-infrared or near-infrared (NIR)-II range, can enable high-resolution in vivo imaging at depths not possible with conventional optical wavelengths.
However, few bioconjugatable probes of the type that have proven invaluable for multiplexed imaging in the visible and NIR range are available for imaging these wavelengths. Using rational design, we have generated persulfonated indocyanine dyes with absorbance maxima at 872 and 1,072 nm through catechol-ring and aryl-ring fusion, respectively, onto the nonamethine scaffold. Multiplexed two-color and three-color in vivo imaging using monoclonal antibody and dextran conjugates in several tumor models illustrate the benefits of concurrent labeling of the tumor and healthy surrounding tissue and lymphatics.
These efforts are enabled by complementary advances in a custom-built NIR/shortwave-infrared imaging setup and software package for multicolor real-time imaging.
KW - Photoluminescence
KW - Fluorescence
KW - Dye
KW - Cyanine
KW - Antibody
KW - Bioconjugate
KW - Conjugate
KW - Quantum yield
KW - Photophysics
KW - Lifetime
KW - Sensor
KW - NIR
KW - SWIR
KW - Mechanism
KW - Imaging
KW - Application
KW - Contrast agent
KW - Bioimaging
PY - 2021
DO - https://doi.org/10.1038/s41592-022-01394-6
VL - 19
IS - 3
SP - 353
EP - 358
PB - Nature Research
AN - OPUS4-54465
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Osiopova, Viktoriia
A1 - Tavernaro, Isabella
A1 - Ge, L.
A1 - Kitzmann, W. R.
A1 - Heinze, K.
A1 - Reithofer, M. R.
A1 - Resch-Genger, Ute
T1 - Complete protection of NIR-luminescent molecular rubies from oxygen quenching in air by L-arginine-mediated silica nanoparticles
N2 - The application of emerging luminophores such as near-infrared (NIR) emissive complexes based on earth-abundant chromium as central ion and triplet-triplet annihilation upconversion (TTA-UC) systems in air as optical reporters for bioimaging or photonic materials for energy conversion requires simple and efficient strategies for their complete protection from uminescence quenching by oxygen. Therefore, we explored the influence of sol–gel synthesis routes on the oxygen protection efficiency of the resulting core and core/shell silica nanoparticles (SiO2 NPs), utilizing the molecular ruby-type luminophores CrPF6 ([Cr(ddpd)2](PF6)3; ddpd = N,N'-dimethyl-N,N'-dipyridin-2-ylpyridin-2,6-diamine) and CrBF4 ([Cr(ddpd)2](BF4)3) with their oxygendependent, but polarity-, proticity-, viscosity-, and concentration-independent luminescence as optical probes for oxygen permeability. The sol–gel chemistry routes we assessed include the classical Stöber method and the underexplored Larginine approach, which relies on the controlled hydrolysis of tetraethoxysilane (TEOS) in a biphasic cyclohexane/water system with the catalyst L-arginine. As demonstrated by luminescence measurements of air- and argon-saturated dispersions of CrPF6- and CrBF4-stained SiO2 NPs of different size and particle architecture, utilizing the luminescence decay kinetics of argon-saturated solutions of CrPF6 and CrBF4 in acetonitrile (ACN) as benchmarks, only SiO2 NPs or shells synthesized by the L-arginine approach provided complete oxygen protection of the CrIII complexes under ambient conditions. We ascribe the different oxygen shielding efficiencies of the silica networks explored to differences in density and surface chemistry of the resulting nanomaterials and coatings, leading to different oxygen permeabilities. Our Larginine based silica encapsulation strategy can open the door for the efficient usage of oxygen-sensitive luminophores and TTA-UC systems as optical reporters and spectral shifters in air in the future.
KW - Quality assurance
KW - Fluorescence
KW - Quantification
KW - Advanced materials
KW - Nano
KW - Quantum yield
KW - NIR
KW - Characterization
KW - Electron microscopy
KW - Silica
KW - Synthesis
KW - Oxygen sensing
KW - Surface
KW - Doping
KW - Lifetime
KW - Cr(III) complex
KW - Shielding
KW - Sensing
PY - 2025
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-638271
DO - https://doi.org/10.26599/NR.2025.94907241
SN - 1998-0000
VL - 18
IS - 3
SP - 1
EP - 13
PB - SciOpen
AN - OPUS4-63827
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Yu, Z.
A1 - Musnier, B.
A1 - Wegner, Karl David
A1 - Henry, M.
A1 - Chovelon, B.
A1 - Desroches-Castan, A.
A1 - Fertin, A.
A1 - Resch-Genger, Ute
A1 - Bailly, S.
A1 - Coll, J.-L.
A1 - Usson, Y,
A1 - Josserand, V.
A1 - Le Gúevel, X.
T1 - High-Resolution Shortwave Infrared Imaging of Vascular Disorders Using Gold Nanoclusters
N2 - We synthesized a generation of water-soluble, atomically precise gold nanoclusters (Au NCs) with anisotropic Surface containing a short dithiol pegylated chain (AuMHA/TDT). The AuMHA/TDT exhibit a high brightness (QY ∼ 6%) in the shortwave infrared (SWIR) spectrum with a detection above 1250 nm.
Furthermore, they show an extended half-life in blood (t1/2ß = 19.54 ± 0.05 h) and a very weak accumulation in organs. We also developed a non-invasive, whole-body vascular imaging system in the SWIR window with high-resolution, benefiting from a series of Monte Carlo image processing. The imaging process enabled to improve contrast by 1 order of magnitude and enhance the spatial Resolution by 59%. After systemic administration of these nanoprobes in mice, we can quantify vessel complexity in depth (>4 mm), allowing to detect very subtle vascular disorders non-invasively in bone morphogenetic protein 9 (Bmp9)-deficient mice. The combination of these anisotropic surface charged Au NCs plus an improved SWIR imaging device allows a precise mapping at high-resolution and an in depth understanding of the organization of the vascular network in live animals.
KW - Nanoparticle
KW - Nanosensor
KW - Fluorescence
KW - Metal cluster
KW - NIR
KW - SWIR
KW - Photophysics
KW - Ligand
KW - Size
KW - Surface chemistry
KW - Quantum yield
KW - Mechanism
KW - Lifetime
KW - Decay kinetics
PY - 2020
DO - https://doi.org/10.1021/acsnano.0c01174
VL - 14
IS - 4
SP - 4973
EP - 4981
PB - ACS Publication
AN - OPUS4-50671
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Sun, C.
A1 - Schäferling, Michael
A1 - Resch-Genger, Ute
A1 - Gradzielski, M.
T1 - Solvothermal Synthesis of Lanthanide-doped NaYF4 Upconversion
N2 - Lanthanide-doped NaYF4 upconversion nano- and microcrystals were synthesized via a facile solvothermal approach. Thereby, the influence of volume ratios of ethylene glycol (EG)/H2O, molar ratios of NH4F/RE3+ (RE3+ represents the total amount of Y3+ and rare-earth dopant ions), Gd3+ ion contents, types of activator dopant ions, and different organic co-solvents on the crystal phase, size, and morphology of the resulting particles were studied systematically. A possible formation mechanism for the growth of crystals of different morphology is discussed. Our results show that the transition from the α- to the β-phase mainly depends on the volume ratio of EG/H2O and the molar ratio of NH4F/RE3+, while the morphology and size could be controlled by the type of organic co-solvent and Gd3+ dopant ions. Furthermore, the reaction time has to be long enough to convert α-NaYF4 into β-NaYF4 during the growth process to optimize the upconversion luminescence. The formation of larger β-NaYF4 crystals, which possess a higher upconversion luminescence than smaller particles, proceeds via intermediates of smaller crystals of cubic structure. In summary, our synthetic approach presents a facile route to tailor the size, Crystal phase, morphology, and luminescence features of upconversion
materials.
KW - Nano
KW - Nanomaterial
KW - Upconversion nanoparticle
KW - Photoluminescence
KW - Lanthanide
KW - Quantum yield
KW - Photophysics
KW - Lifetime
KW - Surface chemistry
KW - Single particle
KW - Brightness
KW - NIR
KW - Synthesis
PY - 2021
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-520307
DO - https://doi.org/10.1002/cnma.202000564
VL - 7
IS - 2
SP - 174
EP - 183
PB - Wiley
AN - OPUS4-52030
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Le Guevel, X.
A1 - Wegner, Karl David
A1 - Würth, Christian
A1 - Baulin, V. A.
A1 - Musnier, B.
A1 - Josserand, V.
A1 - Resch-Genger, Ute
A1 - Koll, J-C
T1 - Tailoring the SWIR emission of gold nanoclusters by surface ligand rigidification and their application in 3D bioimaging
N2 - The influence of solvent polarity and surface ligand rigidification on the SWIR emission profile of gold nanoclusters with an anistropic surface was investigated. A strong enhancement of the SWIR emission band at 1200 nm was observed when measuring in different local environments: in solution, in polymer composites, and in solids. SWIR in vivo imaging of mice assisted by deep learning after intravenous administration of these gold nanoclusters provides high definition pseudo-3D views of vascular blood vessels.
KW - Nano
KW - Nanomaterial
KW - Metal cluster
KW - Photoluminescence
KW - Quantum yield
KW - Photophysics
KW - Lifetime
KW - Sensor
KW - NIR
KW - SWIR
KW - Ligand
KW - Gold
KW - Mechanism
KW - Charge transfer
KW - Enhancement strategy
KW - Imaging
KW - Application
KW - Contrast agent
PY - 2022
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-543582
DO - https://doi.org/10.1039/D1CC06737K
VL - 58
IS - 18
SP - 2967
EP - 2970
PB - RSC
AN - OPUS4-54358
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Resch-Genger, Ute
T1 - Absolute Fluorescence Measurements > 800 nm - Setup Design, Challenges, and Characterization of Semiconductor and Lanthanide-based Nanocrystals
N2 - There is an increasing interest in optical reporters like semiconductor and lanthanide-based nanocrystals with emission > 800 nm and recently also > 1000 nm for bioanalysis, medical diagnostics, and safety barcodes. Mandatory for the comparison of different emitter classes and the rational design of the next generation of reporters for the short wavelength infrared (SWIR) region are reliable and quantitative photoluminescence measurements in this challenging wavelength region. This is of special relevance for nanocrystalline emitters like semiconductor quantum dots and rods as well as for upconversion and downconversion nanocrystals, where surface states and the accessibility of emissive states by quenchers largely control accomplishable quantum yields and hence, signal sizes and detection sensitivities from the reporter side. Such measurements are currently hampered by the lack of suitable methods and standards for instrument calibration and validation as well as by the lack of quantum yield standards with emission > 800 nm and especially > 1000 nm.
In this respect, we present the design of integrating sphere setups for absolute and excitation power densitydependent measurements of emission spectra and quantum yields in the wavelength region of 650 to 1650 nm
including calibration strategies and first candidates for potential fluorescence standards. Subsequently, the photoluminescence properties of different types of nanocrystals are presented and discussed including absolute photoluminescence measurements of upconversion and down conversion emission in different solvents.
T2 - MRS 2017
CY - Boston, MA, USA
DA - 26.11.2017
KW - Upconversion
KW - Nanoparticle
KW - Absolute fluorometry
KW - Integrating sphere spectroscopy
KW - NIR
KW - IR
KW - Fluorescence
KW - Surface chemistry
KW - Deactivation pathways
KW - Semiconductor quantum dot
KW - SWIR
KW - Quantum yield
KW - Energy transfer
KW - Size
PY - 2017
AN - OPUS4-43202
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Wang, Cui
A1 - Ebel, Kenny
A1 - Heinze, Katja
A1 - Resch-Genger, Ute
A1 - Bald, Ilko
T1 - Quantum Yield of DNA Strand Breaks under Photoexcitation of a Molecular Ruby
N2 - Photodynamic therapy (PDT) used for treating cancer relies on the generation of highly reactive oxygen species, for example, singlet oxygen 1O2, by light-induced excitation of a photosensitizer (PS) in the presence of molecular oxygen, inducing DNA damage in close proximity of the PS. Although many precious metal complexes have been explored as PS for PDT and received clinical approval, only recently, the potential of photoactive complexes of nonnoble metals as PS has been discovered. Using the DNA origami technology that can absolutely quantify DNA strand break cross sections, we assessed the potential of the luminescent transition metal complex [Cr(ddpd)2]3+ (ddpd=N,N’-dimethyl-N,N’-dipyridine-2-ylpyridine-2,6-diamine) to damage DNA in an air-saturated aqueous environment upon UV/Vis illumination. The quantum yield for strand breakage, that is, the ratio of DNA strand breaks to the number of absorbed photons, was determined to 1–4%, indicating efficient transformation of photons into DNA strand breaks by [Cr(ddpd)2]3+.
KW - Fluorescence
KW - Synthesis
KW - Production
KW - Optical spectroscopy
KW - Ligand
KW - Photophysics
KW - Cr(III)
KW - Mechanism
KW - NIR
KW - PDT
KW - Singlet oxygen
KW - DNA
KW - Origami
KW - Quantum yield
PY - 2023
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-573631
DO - https://doi.org/10.1002/chem.202203719
SP - 1
EP - 7
AN - OPUS4-57363
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Richter, Maria
A1 - Güttler, Arne
A1 - Pauli, Jutta
A1 - Vogel, K.
A1 - Homann, Christian
A1 - Würth, Christian
A1 - Resch-Genger, Ute
T1 - Extending certified spectral fluorescence standards for the calibration and performance validation of fluorescence instruments to the NIR—closing the gap from 750 to 940 nm with two novel NIR dyes
N2 - Fluorescence techniques such as fluorescence spectroscopy, microfluorometry, and fluorescence microscopy, providing spectral, intensity, polarization, and lifetime information, are amongst the most broadly utilized analytical methods in the life and materials sciences. However, the measured fluorescence data contain sample- and instrument-specific contributions, which hamper their comparability across instruments and laboratories. Comparable, instrument-independent fluorescence data require the determination of the fluorescence instrument’s wavelength-dependent spectral responsivity, also termed emission correction curve, for the same instrument settings as those used for the fluorescence measurements as a prerequisite for the subsequent correction of the measured instrument-specific data. Such a spectral correction is essential for the performance comparison of different fluorescent labels and reporters, quantitative fluorescence measurements, the determination of the fluorescence quantum yield, and the spectroscopic measure for the fluorescence efficiency of a fluorophore. Simple-to-use tools for obtaining emission correction curves are chromophore-based reference materials (RMs), referred to as fluorescence standards, with precisely known, preferably certified instrument-independent fluorescence spectra. However, for the increasingly used near-infrared (NIR) wavelength region >700 nm, at present, no spectral fluorescence standards are available. To close this gap, we developed two novel spectral fluorescence standards, BAM F007 and BAM-F009, with broad emission bands from about 580 to 940 nm in ethanolic solution. These liquid fluorescence standards currently under certification, which will be released in 2025, will expand the wavelength range of the already available certified Calibration Kit BAM F001b-F005b from about 300–730 to 940 nm. In this research article, we will detail the criteria utilized for dye and matrix selection and the homogeneity and stability tests accompanying dye certification as well as the calculation of the wavelength-dependent uncertainty budgets of the emission spectra BAM F007 and BAM-F009, determined with the traceably calibrated BAM reference spectrofluorometer. These fluorescence standards can provide the basis for comparable fluorescence measurements in the ultraviolet, visible, and NIR for the fluorescence community.
KW - Quality assurance
KW - Reference material
KW - Fluorescence
KW - Dye
KW - Traceability
KW - Metrology
KW - Calibration
KW - Reference data
KW - Reference product
KW - Digital certificate
KW - NIR
KW - Instrument performance validation
PY - 2025
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-626317
DO - https://doi.org/10.1007/s00216-024-05723-w
SN - 1618-2650
SP - 1
EP - 15
PB - Springer
AN - OPUS4-62631
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Ahiboz, D.
A1 - Andresen, Elina
A1 - Manley, P.
A1 - Resch-Genger, Ute
A1 - Würth, Christian
A1 - Becker, C.
T1 - Metasurface-Enhanced Photon Upconversion upon 1550 nm Excitation
N2 - Photon upconversion upon 1550 nm excitation is of high relevance for applications in the third biological excitation window, for photovoltaics beyond current limitations, and enables appealing options in the field of glass Fiber telecommunications. Trivalent doped erbium ions (Er3+) are the material of choice for 1550 nm excited upconversion, however, they suffer from a low absorption cross-section and a low brightness. Therefore, the ability of Silicon metasurfaces to provide greatly enhanced electrical near-fields is employed to enable efficient photon upconversion even at low external Illumination conditions. Hexagonally shaped β-NaYF4:Er3+ nanoparticles are placed on large-area silicon metasurfaces designed to convert near-infrared (1550 nm) to visible light. More than 2400-fold enhanced photon upconversion luminescence is achieved by using this metasurface instead of a planar substrate.
With the aid of optical simulations based on the finite-element method, this result is attributed to the coupling of the excitation source with metasurface resonances at appropriate incident angles. Analysis of the excitation power density dependence of upconversion luminescence and red-to-green-emission ratios enables the estimation of nanoscale near-field enhancement on the metasurface. The findings permit the significant reduction of required external excitation intensities for photon upconversion of 1550 nm light, opening perspectives in biophotonics, telecommunication, and photovoltaics.
KW - Nano
KW - Nanomaterial
KW - Upconversion nanoparticle
KW - Lanthanide
KW - Photoluminescence
KW - Quantum yield
KW - Photophysics
KW - Lifetime
KW - Sensor
KW - Excitation power density
KW - Single particle
KW - Brightness
KW - NIR
KW - Mechanism
KW - Single enhancement
KW - SWIR
KW - Method
PY - 2021
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-537193
DO - https://doi.org/10.1002/adom.202101285.
SN - 2195-1071
VL - 9
IS - 24
SP - 2101285
PB - Wiley-VCH-GmbH
AN - OPUS4-53719
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Resch-Genger, Ute
A1 - Carl, F.
A1 - Grauel, Bettina
A1 - Pons, Monica
A1 - Würth, Christian
A1 - Haase, M.
T1 - LiYF4:Yb/LiYF4 and LiYF4:Yb,Er/LiYF4 core/shell nanocrystals with luminescence decay times similar to YLF laser crystals and the upconversion quantum yield of the Yb,Er doped nanocrystals
N2 - We developed a procedure to prepare luminescent LiYF4:Yb/LiYF4 and LiYF4:Yb,Er/LiYF4 core/shell nanocrystals with a size of approximately 40 nm revealing luminescence decay times of the dopant ions that approach those of high-quality laser crystals of LiYF4:Yb (Yb:YLF) and LiYF4:Yb,Er (Yb,Er:YLF) with identical doping concentrations. As the luminescence decay times of Yb3+ and Er3+ are known to be very sensitive to the presence of quenchers, the long decay times of the core/shell nanocrystals indicate a very low number of defects in the core particles and at the core/shell interfaces. This improvement in the performance was achieved by introducing two important modifications in the commonly used oleic acid based synthesis. First, the shell was prepared via anewly developed method characterized by a very low nucleation rate for particles of pure LiYF4 shell material. Second, anhydrous acetates were used as precursors and additional drying steps were applied to reduce the incorporation of OH− in the crystal lattice, known to quench the emission of Yb3+ ions. Excitation power density (P)-dependent absolute measurements of the upconversion luminescence quantum yield (Φ,UC) of LiYF4:Yb,Er/LiYF4 core/shell particles reveal a maximum value of 1.25% at P of 180 W·cm−2.
Although lower than the values reported for NaYF4:18%Yb,2%Er core/shell nanocrystals with comparable sizes, these Φ, UC values are the highest reported so far for LiYF4:18%Yb,2%Er/LiYF4 nanocrystals without additional dopants. Further improvements May nevertheless be possible by optimizing the dopant concentrations in the LiYF4 nanocrystals.
KW - Nano
KW - Crystal
KW - Quantum yield
KW - LiYF4
KW - Synthesis
KW - Lifetime
KW - Fluorescence
KW - NIR
KW - Photoluminescence
KW - Lanthanide
KW - Upconversion nanoparticle
KW - Nanomaterial
PY - 2020
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-515395
DO - https://doi.org/10.1007/s12274-020-3116-y
SN - 1998-0124
VL - 14
IS - 3
SP - 797
EP - 806
PB - Springer
AN - OPUS4-51539
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Resch-Genger, Ute
T1 - Assessing different types of silica networks for the complete protection of nir luminescent molecular rubies from oxygen quenching in air
N2 - The application of emerging luminophores such as near-infrared (NIR) emissive earth-abundant chromium(III) (CrIII) complexes and triplet-triplet annihilation upconversion (TTA-UC) systems in air as optical reporters for bioimaging or photonic materials for energy conversion requires simple and efficient strategies for their complete protection from luminescence quenching by oxygen. Therefore, we explored the influence of sol-gel synthesis routes on the oxygen protection efficiency of the resulting core and core/shell silica nanoparticles (SiO2 NPs), utilizing the molecular ruby-type luminophores CrPF6 ([Cr(ddpd)2](PF6)3; ddpd = N,N’-dimethyl- N,N’-dipyridin-2-ylpyridin-2,6-diamine) and CrBF4 ([Cr(ddpd)2](BF4)3) with their oxygen-dependent, but polarity-, proticity-, viscosity-, and concentration-independent luminescence as optical probes for oxygen permeability. The sol-gel chemistry routes we assessed include the classical Stöber method and the underexplored larginine approach, which relies on the controlled hydrolysis of tetraethoxysilane (TEOS) in a biphasic cyclohexane/water system with the catalyst l-arginine. As demonstrated by luminescence measurements of air- and argon-saturated dispersions of CrPF6- and CrBF4-stained SiO2 NPs of different size and particle architecture, utilizing the luminescence decay kinetics of argon-saturated solutions of CrPF6 and CrBF4 in acetonitrile (ACN) as benchmarks, only SiO2 NPs or shells synthesized by the l-arginine approach provided complete oxygen protection of the CrIII complexes under ambient conditions. We ascribe the different oxygen shielding efficiencies of the silica networks explored to differences in density and surface chemistry of the resulting nanomaterials and coatings, leading to different oxygen permeabilities. Our l-arginine based silica encapsulation strategy can open the door for the efficient usage of oxygen-sensitive luminophores and TTA-UC systems as optical reporters and spectral shifters in air in the future.
T2 - eMRS Strasbourg
CY - Strasbourg, France
DA - 26.05.2025
KW - Quality assurance
KW - Fluorescence
KW - Nano
KW - Particle
KW - Synthesis
KW - Quantum yield
KW - NIR
KW - Mechanism
KW - Characterization
KW - Electron microscopy
KW - Silica
KW - Oxygen sensing
KW - Surface
KW - Doping
KW - Lifetime
KW - Cr(III) complex
PY - 2025
AN - OPUS4-63300
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Resch-Genger, Ute
A1 - Wegner, Karl David
A1 - Kalot, G.
A1 - Busser, B.
A1 - Pliquett, J.
A1 - Köster, U.
A1 - Koll, J. C.
A1 - Denat, F.
A1 - Bodio, E.
A1 - Goze, C.
A1 - Sacey, L.
T1 - NIR aza-BODIPY: a new vector for boron neutron capture therapy (BNCT)
N2 - Boron neutron capture therapy (BNCT) relies on the activation of 10B by thermal neutrons, which results in small highly energetic particle emission inducing cancer cells damage. However, in order to overcome the limits of the currently used BNCT agents, it is necessary to design new systems, which can specifically accumulate and deliver a sufficient amount of 10B in tumors. In this study, we designed a 10B-BSH-containing aza-BODIPY (aza-SWIR-BSH). It enabled the efficient vectorization of clinically used 10B-BSH to the tumor, resulting in higher therapeutic activity than the 10B-BSH alone.
T2 - EMIM 2021
CY - Göttingen, Germany
DA - 24.08.2021
KW - Flourescence
KW - Optical probe
KW - Dye
KW - Photophysics
KW - Quantum yield
KW - Mechanism
KW - NIR
KW - SWIR
KW - Imaging
KW - Method
KW - Quality assurance
KW - BODIPY
KW - Boron Neutron Capture Therapy (BNCT)
KW - Medicine
KW - Life sciences
PY - 2021
AN - OPUS4-53731
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Resch-Genger, Ute
A1 - Pilch, A.
A1 - Würth, Christian
A1 - Kaiser, Martin
A1 - Wawrzynczyk, D.
A1 - Kurnatowska, M.
A1 - Arabasz, S.
A1 - Prorok, K.
A1 - Samoc, M.
A1 - Strek, W.
A1 - Bednarkiewicz, A.
T1 - Shaping luminescent properties of Yb3+ and Ho3+ co-doped upconverting core-shell ß-NaYF4 nanoparticles by dopant distribution and spacing
N2 - At the core of luminescence color and lifetime Tuning of rare earth doped upconverting nanoparticles (UCNPs), is the understanding of the Impact of the particle architecture for commonly used sensitizer (S) and activator (A) Ions. In this respect, a series of core@Shell NaYF4 UCNPs doped with Yb3+ and Ho3+ ions are presented here, where the same dopant concentrations are distributed in different particle architectures following the scheme: YbHo core and YbHo@..., ...@YbHo, Yb@Ho, Ho@Yb, YbHo@Yb, and Yb@YbHo core-Shell NPs. As refealed by quantitative steady-state and time-resolved luminescence studies, the relative spatial Distribution of the A and S ions in the UCNPs and their protection from surface quenching has a critical Impact on ther luminescence characteristics. Although the increased amount of Yb3+ Ions boosts UCNP Performance by amplifying the Absorption, the Yb3+ ions can also efficiently dissipate the energy stored in the material through energy Migration to the surface, thereby reducing the Overall energy Transfer Efficiency to the activator ions. The results provide yet another proof that UC Phosphor chemistry combined with materials Engineering through intentional core@shell structures may help to fine-tune the luminescence Features of UCNPs for their specific future applications in biosensing, bioimaging, photovoltaics, and Display technologies.
KW - Fluorescence
KW - Upconversion
KW - NIR
KW - Nonlinear
KW - Nanoparticle
KW - Surface chemistry
KW - Quantum yield
KW - Liftetime
KW - Nanocrystal
KW - Lanthanide
KW - Ho(III)
KW - Yb(III)
KW - Mechanism
KW - Absolute flourescence
KW - Excitation power density dependence
PY - 2017
DO - https://doi.org/10.1002/smll.201701635
SN - 1613-6810
VL - 13
IS - 47
SP - 1701635, 1
EP - 13
PB - WILEY-VCH Verlag GmbH & co. KGaA
CY - Weinheim
AN - OPUS4-43629
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Resch-Genger, Ute
T1 - Measurements of Photoluminescence Quantum Yields of Scattering LED Converter Materials
N2 - How to Get it Right with the Absolute Measurement of Photoluminescence Quantum Yields of Scattering LED Converter Materials Saskia Fiedler+,a, Florian Frenzel+,a, Christian Würth a, Isabella Tavernaro a, Michelle Grüne c, Stefan Schweizer c,d, Axel Engel e, and Ute Resch-Genger a* a Division Biophotonics, Federal Institute for Materials Research and Testing (BAM), Richard-Willstaetter-Strasse 11, D-12489 Berlin, Germany; email: ute.resch@bam.de b Present address: Photonic Materials, NWO-Institute AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands c Faculty of Electrical Engineering, South Westphalia University of Applied Sciences, Lübecker Ring 2, 59494, Soest, Germany d Fraunhofer Application Center for Inorganic Phosphors, Branch Lab of Fraunhofer Institute for Microstructure of Materials and Systems IMWS, Lübecker Ring 2, 59494, Soest, Germany e Schott AG Technical Services, Hattenbergstrasse 10, D-55122 Mainz, Germany Optical measurements of scattering materials such as luminescent nano- and microparticles and phosphors dispersed in liquid and solid matrices play an important role in energy conversion, solid-state lighting, medical diagnostics, and security barcoding. A key performance parameter is the photoluminescence quantum yield QY, i.e., the number of emitted per number of absorbed photons. QY of transparent luminophore solutions can be obtained relative to a fluorescence QY standard of known QY, meanwhile available as certified reference materials.[1] The determination of QY of scattering liquid and solid samples like nanoparticle dispersions, phosphors, and optoceramics requires, however, absolute measurements with an integrating sphere setup. Despite the need for reliable absolute QY measurements, no interlaboratory comparison (ILCs) on measurement uncertainties has been performed and scattering standards with known QY are not available. We present the results of an ILC of 3 labs from academia and industry on measurements of transparent and scattering dye solutions and solid phosphors and converter materials like YAG:Ce optoceramics with commercial stand-alone integrating sphere setups of different illumination and detection geometries. Special emphasis was dedicated to the influence of measurement geometry, optical properties of the blank for determining the number of incident photons absorbed by the sample, and sample-specific surface roughness. Matching QY values could be obtained for transparent dye solutions and scattering dispersions with a blank with scattering properties closely matching those of the sample, QY measurements of optoceramic samples with different blanks revealed substantial differences of more than 20 %. Based on our data, we recommend non-absorbing blank materials with a high reflectivity (>95 %) such as a 2 mm-thick PTFE target placed on the sample holder as blanks.
T2 - eMRS
CY - Strasbourg, France
DA - 26.05.2025
KW - Quality assurance
KW - Fluorescence
KW - Nano
KW - Particle
KW - Quantum yield
KW - NIR
KW - Characterization
KW - Electron microscopy
KW - Film
KW - Integrating sphere spectroscopy
KW - Calibration
KW - Lifetime
KW - Advanced materials
KW - LED converter
KW - YAG:Ce
KW - ILC
KW - Measurement uncertainty
KW - Absolute quantum yield
PY - 2025
AN - OPUS4-63327
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Hoffmann, Katrin
A1 - Nirmalananthan-Budau, Nithiya
A1 - Resch-Genger, Ute
T1 - Fluorescence calibration standards made from broadband emitters encapsulated in polymer beads for fluorescence microscopy and flow cytometry
N2 - We present here the design and characterization of a set of spectral calibration beads. These calibration beads are intended for the determination and regular control of the spectral characteristics of fluorescence microscopes and other fluorescence measuring devices for the readout of bead-based assays. This set consists of micrometer-sized polymer beads loaded with dyes from the liquid Calibration Kit Spectral Fluorescence Standards developed and certified by BAM for the wavelength-dependent Determination of the spectral responsivity of fluorescencemeasuring devices like spectrofluorometers. To cover the wavelength Region from 400 to 800 nm, two new near-infrared emissive dyes were included, which were spectroscopically characterized in solution and encapsulated in the beads. The resulting set of beads presents the first step towards a new platform of spectral calibration beads for the determination of the spectral characteristics of fluorescence instruments like fluorescence microscopes, FCM setups, and microtiter plate readers, thereby meeting the increasing demand for reliable and comparable fluorescence data especially in strongly regulated areas, e.g., medical diagnostics. This will eventually provide the basis for standardized calibration procedures for imaging systems as an alternative to microchannel slides containing dye solutions previously reported by us.
KW - Fluorescence standard
KW - Fluorescence
KW - Dye
KW - Microscopy
KW - Bead
KW - Particle
KW - NIR
KW - calibration
KW - Quality assurance
KW - Traceability
PY - 2020
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-508117
DO - https://doi.org/10.1007/s00216-020-02664-y
SN - 1618-2642
VL - 412
IS - 24
SP - 6499
EP - 6507
PB - Springer
AN - OPUS4-50811
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Resch-Genger, Ute
T1 - Methods for the determination of the optical properties and the surface chemistry of fluorescent particles
N2 - Fluorescent particles like nm- and m-sized polymeric beads doped or labeled with different types of fluorophores and nanocrystalline systems like quantum dots and upconversion phosphors emitting in the visible (vis), near-infrared (NIR), and IR (infrared) region are of increasing importance as fluorescent reporters for bioanalysis and medical diagnostics. The assessment and comparison of material performance and the development of rational design strategies for improved systems requires suitable spectroscopic tools for the determination of signal-relevant optical properties and analytical tools for the determination of the number of surface groups, ligands, biomolecules and /or fluorophores per bead. In this respect, suitable spectroscopic tools for the characterization of the optical properties of such materials like photoluminescence quantum yields and brightness values and the determination of their surface chemistry are introduced. This includes integrating sphere setups for absolute measurements of fluorescence quantum yields of liquid and solid, transparent and scattering materials in the wavelength region of 350 nm to 1600 nm at varying excitation power densities for the study of multi-photon processes and simple optical assays, validated by comparison with established analytical techniques relying on different detection principles. Here, different examples for the optical and analytical characterization of different types of nanoscale reporters are presented.
T2 - MoLife Research Seminar
CY - Bremen, Germany
DA - 26.04.2016
KW - Optical assay
KW - Fluorescence
KW - Integrating sphere spectroscopy
KW - Quantum yield
KW - NIR
KW - IR
KW - Optical spectroscopy
KW - Nanomaterials
KW - Semiconducor nanocrystals
KW - Upconversion nanocrystals
KW - Surface analysis
KW - Ligand analysis
PY - 2016
AN - OPUS4-35954
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Pauli, Jutta
A1 - Hoffmann, Katrin
A1 - Würth, Christian
A1 - Behnke, Thomas
A1 - Resch-Genger, Ute
T1 - Standardization of fluorescence measurements in the UV/vis/NIR/IR
N2 - Photoluminescence techniques are amongst the most widely used Tools in the life sciences, with new and exciting applications in medical diagnostics and molecular Imaging continuously emerging. Advantages include their comparative ease of use, unique sensitivity, non-invasive character, and potential for Multiplexing, remote sensing, and miniaturization. General drawbacks are, however, signals, that contain unwanted wavelength- and polarization contributions from Instrument-dependent effects, which are also time-dependent due to aging of Instrument-components, and difficulties to measure absolute flourescence entensities. Moreover, scattering Systems require Special measurement geometries and the interest in new optical Reporters with Emission > 1000 nm strategies for reliable measurements in the second diagnostic for the comparison of material Performance and the rational designg of new flourophores with improved properties.
Here, we present strategies to versatile method-adaptable liquid and solid flourescence Standards for different flourescence paramters including traceable Instrument calibration procedures and the design of integrating spere setups for the absolute measurements of emission spectra and Quantum yields in the wavelength Region of 350 to 1600 nm. Examples are multi-Emitter glasses, spectral flourescence Standards, and quantum yield Standards for the UV/vis/NIR.
T2 - Conference on Molecular-Guided Surgery - Molecules, Devices, and Applications III
CY - San Francisco, CA, USA
DA - 28.01.2017
KW - Fluorescence
KW - Reference material
KW - Standard
KW - Calibration
KW - Nanoparticle
KW - Absolute flourometry
KW - Integrating sphere spectroscopy
KW - NIR
KW - IR
KW - Quantum yield standard
KW - Emission standards
PY - 2017
SN - 978-1-5106-0539-8
DO - https://doi.org/10.1117/12.2255728
SN - 0277-786X
VL - 10049
SP - 1
PB - Proceedings of SPIE
AN - OPUS4-41783
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - GEN
A1 - Resch-Genger, Ute
A1 - Richter, Maria
A1 - Güttler, Arne
A1 - Pauli, Jutta
A1 - Vogel, K.
A1 - Homann, Christian
A1 - Würth, Christian
T1 - Extending Certified Spectral Fluorescence Standards for the Calibration and Performance Validation of Fluorescence Instruments to the NIR – Closing the Gap from 750 nm to 940 nm with Two Novel NIR Dyes
N2 - Fluorescence methods provide spectral, intensity, polarization, and lifetime information, which contain sample- and instrument-specific contributions. Fluorescence data, comparable across instruments and laboratories, require validated calibration procedures and certified fluorescence standards.
KW - Quality assurance
KW - Reference material
KW - Fluorescence
KW - Dye
KW - Traceability
KW - Metrology
KW - Calibration
KW - Reference data
KW - Reference product
KW - Digital certificate
KW - NIR
KW - Instrument performance validation
PY - 2025
SP - 1
EP - 4
PB - Springer Nature
CY - London
AN - OPUS4-62739
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Andreato, E.
A1 - Panov, N.
A1 - Artiga, A.
A1 - Osipova, Viktoriia
A1 - Resch-Genger, Ute
A1 - Ximendes, E.
A1 - Molina, P.
A1 - Canton, P.
A1 - Marin, R.
T1 - Indium-Based Fluoride Nanoparticles Doped with Chromium for Near-Infrared Luminescence
N2 - Transition metal (TM) and rare earth (RE) ion-doped nanoparticles (NPs) are photoluminescent materials of technological relevance in bioimaging, sensing, and light conversion. Fluoride NPs are particularly attractive in this context, since they combine low-energy phonons, high chemical stability, optical transparency, size, and architecture tunability. Yet, nearly all reported colloidal fluoride NPs (e.g., NaYF4 and LiYF4) can only be efficiently doped with RE3+ and not with luminescent TM ions. Herein, we contribute to filling this gap in materials science by reporting Na3InF6 NPs doped with Cr3+ as a model luminescent TM ion. We unveil the heat-driven NP formation mechanism, which involves a cubic-to-monoclinic phase conversion, similarly to the cubic-tohexagonal phase conversion in NaYF4. Reaction temperatures above 225 °C and reaction time have a limited impact on the NP morphology, while the amount of fluoride precursor and oleylamine grants control over the NP size. After verifying that Na3InF6 NPs show negligible cytotoxicity toward U-87 cell line, we study the optical properties of these NPs upon Cr3+ doping.
Temperature-dependent photoluminescence measurements indicate that Cr3+ ions experience a weak crystal field in the Na3InF6 host lattice, while their photoluminescence lifetime varies linearly in the 20−50 °C range. These results set the ground for further studies of photoluminescent TM-doped fluoride NPs, toward their applications in bioimaging, sensing, and light-converting devices.
KW - Quality assurance
KW - Fluorescence
KW - Traceability
KW - Nano
KW - Particle
KW - Synthesis
KW - Quantum yield
KW - NIR
KW - Mechanism
KW - Characterization
KW - XRD
KW - Phase transition
KW - Ligand
KW - Surface
KW - Doping
KW - Lifetime
PY - 2025
DO - https://doi.org/10.1021/acs.chemmater.4c03335
SN - 1520-5002
SP - 1
EP - 14
PB - American Chemical Society
AN - OPUS4-63073
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Homann, Christian
A1 - Peeters, Régis
A1 - Mirmajidi, Hana
A1 - Berg, Jessica
A1 - Fay, Michael
A1 - Rodrigues, Lucas Carvalho Veloso
A1 - Radicchi, Eros
A1 - Jain, Akhil
A1 - Speghini, Adolfo
A1 - Hemmer, Eva
T1 - Rapid microwave-assisted synthesis of morphology-controlled luminescent lanthanide-doped Gd2O2S nanostructures
N2 - Gadolinium oxysulfide (Gd2O2S) is an attractive material of demonstrated suitability for a variety of imaging applications, leveraging its magnetic, scintillating, and luminescent properties, particularly when doped with optically active lanthanide ions (Ln3+). For many of these applications, control over size and morphology at the nanoscale is crucial. This study demonstrates the rapid microwave-assisted Synthesis of colloidal Ln2O2S (Ln = Gd and dopants Yb, Er, Tb) nanostructures in as little as 20 min. Structural characterization using X-ray diffraction analysis (XRD), Raman spectroscopy, as well as Transmission electron microscopy (TEM), including elemental mapping via energy dispersive X-ray spectroscopy (EDS), unveiled the key role of elemental sulphur (S8) in the reaction mixtures for materials growth. By systematically varying the Ln-to-S ratio from 1 : 0.5 to 1 : 15, controlled morphologies ranging from triangular nanoplatelets to berry- and flower-like shapes were achieved. Doping with Er3+/Yb3+ endowed the nano-triangles with upconverting and near-infrared emitting properties. Tb3+-doped Gd2O2S exhibited the characteristic green Tb3+ emission under UV excitation, while also showing X-ray excited optical luminescence (XEOL), rendering the material interesting as a potential nano-scintillator.
KW - Upconversion
KW - Microwave-assisted synthesis
KW - Synthesis
KW - Fluorescence
KW - Nano
KW - Particle
KW - NIR
KW - XRD
KW - X-ray fluoressence
KW - Morphology control
KW - Raman
PY - 2025
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-647907
DO - https://doi.org/10.1039/D5TC01646K
SN - 2050-7526
VL - 13
IS - 35
SP - 18492
EP - 18507
PB - Royal Society of Chemistry (RSC)
AN - OPUS4-64790
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Daly, H.C
A1 - Matikonda, S.S
A1 - Steffens, H.C
A1 - Rühle, Bastian
A1 - Resch-Genger, Ute
A1 - Ivanic, J.
A1 - Schermann, M.J
T1 - Daly_Photochem Photobiol 2021_Ketone Incorporation Extends the Emission Properties of the Xanthene Scaffold
N2 - Imaging in the shortwave-infrared region (SWIR, λ = 1000–2500 nm) has the potential to enable deep tissue imaging with high resolution. Critical to the development of these Methods is the identification of low molecular weight, biologically compatible fluorescent probes that emit beyond 1000 nm.
Exchanging the bridging oxygen atom on the xanthene scaffold (C10’ position) with electron withdrawing groups has been shown to lead to significant redshifts in absorbance and emission. Guided by quantum chemistry computational modeling studies, we investigated the installation of a Ketone bridge at the C10’ position. This simple modification extends the absorbance maxima to 860 nm and the emission beyond 1000 nm, albeit with reduced photon output. Overall, These studies demonstrate that broadly applied xanthene dyes can be extended into the SWIR range.
KW - Flourescence
KW - Optical probe
KW - Dye
KW - Photophysics
KW - Quantum yield
KW - Mechanism
KW - NIR
KW - SWIR
KW - Imaging
KW - Reliability
KW - Method
KW - Quality assurance
PY - 2021
DO - https://doi.org/10.1111/php.13544
SN - 1751-1097
VL - 98
IS - 2
SP - 325
EP - 333
PB - Wiley Online Library
AN - OPUS4-54080
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Resch-Genger, Ute
A1 - Würth, Christian
A1 - Frenzel, Florian
A1 - Weigert, Florian
A1 - Andresen, Elina
A1 - Grauel, Bettina
A1 - Wegner, Karl David
T1 - Semiconductor (SCNC) & Upconversion Nanocrystals (UCNC) – Optical Properties, Applications & Challenges
N2 - Inorganic nanocrystals with linear and nonlinear luminescence in the ultraviolet, visible, near infrared and shortwave infrared like semiconductor quantum dots and spectrally shifting lanthanide-based nanophosphors have meanwhile found applications in the life and material sciences ranging from optical reporters for bioimaging and sensing over security barcodes to solid state lighting and photovoltaics. These nanomaterials commonly have increasingly sophisticated core/shell particle architectures with shells of different chemical composition and thickness to minimize radiationless deactivation at the particle surface that is usually the main energy loss mechanism [1]. For lanthanide-based spectral shifters, particularly for very small nanoparticles, also surface coatings are needed which protect near-surface lanthanide ions from luminescence quenching by high energy vibrators like O-H groups and prevent the disintegration of these nanoparticles under high dilution conditions. [2,3,4]. The identification of optimum particle structures requires quantitative spectroscopic studies focusing on the key performance parameter photoluminescence quantum yield [5,6], ideally flanked by single particle studies to assess spectroscopic inhomogeneities on a particle-to-particle level for typical preparation methods [7], Moreover, in the case of upconversion nanoparticles with a multi-photonic and hence, excitation power density (P)-dependent luminescence, quantitative luminescence studies over a broad P range are required to identify particle architectures that are best suited for applications in fluorescence assays up to fluorescence microscopy. Here, we present methods to quantify the photoluminescence of these different types of emitters in the vis/NIR/SWIR and as function of Pand demonstrate the importance of such measurements for a profound mechanistic understanding of the nonradiative deactivation pathways in semiconductor and upconversion nanocrystals of different size and particle architecture in different environments.
T2 - 27th Annual Meeting of the Slovenian Chemical Society
CY - Portoroz-Portorose, Slovenia
DA - 21.09.2021
KW - Nano
KW - Nanomaterial
KW - Upconversion nanoparticle
KW - Lanthanide
KW - Photoluminescence
KW - Quantum yield
KW - Photophysics
KW - Lifetime
KW - Surface chemistry
KW - Single particle
KW - Brightness
KW - NIR
KW - Synthesis
KW - Semiconductur
KW - Quantum dot
KW - Nanocrystal
KW - SWIR
PY - 2021
AN - OPUS4-53723
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Pauli, Jutta
A1 - Würth, Christian
A1 - Güttler, Arne
A1 - Resch-Genger, Ute
T1 - Reliable Determination of the Signal-Relevant Spectroscopic Key Characteristics of Luminescent Reporters and Optical Probes for Imaging in the vis/NIR/SWIR
N2 - Introduction. Comparing different emitter classes and rationally designing the next generation of molecular and nanoscale probes for bioimaging applications require accurate and quantitative methods for the measurement of the key parameter photoluminescence quantum yield f.1 f equals the number of emitted per number of absorbed photons. This is particularly relevant for increasingly used fluorescence imaging in the short wave-infrared region (SWIR) ≥ 900 nm providing deeper penetration depths, a better image resolution, and an improved signal-to-noise or tumor-to-background ratio.2, 3 However, spectroscopic measurements in the SWIR are more challenging and require specific calibrations and standards.
T2 - EMIM 2021
CY - Göttingen, Germany
DA - 24.08.2021
KW - Fluorescence
KW - Optical probe
KW - Dye
KW - Photophysics
KW - Quantum yield
KW - Mechanism
KW - NIR
KW - SWIR
KW - Imaging
KW - Reference material
KW - Reliability
KW - Nano
KW - Particle
KW - Method
KW - Quality assurance
PY - 2021
AN - OPUS4-53233
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Resch-Genger, Ute
T1 - Design and Quantitative Characterization of Functional Molecular Chromophores and Nanomaterials with UV/vis/NIR/IR Emission – An Overview of Research Activities in Division Biophotonics
N2 - In the focus of division Biophotonics are the design, preparation, analytical and spectroscopic characterization, and application of molecular and nanoscale
functional materials, particularly materials with a photoluminescence in the visible, near infrared (NIR) and short-wave infrared (SWIR). This includes optical reporters for bioimaging and sensing, security and authentication barcodes, and materials for solid state lighting, energy conversion, and photovoltaics. For the identification of optimum particle structures quantitative spectroscopic studies are performed under application-relevant conditions, focusing on the key performance parameter photoluminescence quantum yield. In addition, simple, cost-efficient, and standardizable strategies for quantifying functional groups on the surface of nano- and microparticles are developed, here with a focus on optical assays and electrochemical titration methods, cross-validated by more advanced methods such as quantitative NMR. In addition, reference materials and reference products are developed for optical methods, particularly luminescence techniques, and for analytical methods utilized for the characterization of nanomaterials.
T2 - Projekttreffen Nile-Chrome 2.0
CY - Mainz, Germany
DA - 11.12.2023
KW - Fluorescence
KW - Quantum yield
KW - Optical spectroscopy
KW - Reference material
KW - Reference data
KW - Quality assurance
KW - Dye
KW - Reference product
KW - NIR
KW - SWIR
KW - Nano
KW - Particle
KW - Silica
KW - Polymer
KW - Surface group analysis
KW - Sensor molecules
PY - 2023
AN - OPUS4-59123
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Resch-Genger, Ute
T1 - Absolute spectroscopic characterization of the optical properties of semiconductor and upconversion nanocrystals in the vis and IR
N2 - Nanocrystalline fluorophores like semiconductor quantum dots and rods and recently also lanthanide-based upconversion phosphors with emission in the visible (vis), near-infrared (NIR), and IR (infrared) region are increasingly being used in bioimaging studies and fluorescence assays as well as in photovoltaics and solid state lighting. The assessment and comparison of material performance as well as the development of rational design strategies for improved systems require spectroscopic tools, which enable the determination of the signal-relevant optical properties like photoluminescence quantum yields and brightness values. In the case of nonlinear fluorescence as shown by upconversion materials, such measurements must be also performed as function of excitation power density. In this work, we report on methods for the absolute determination of the photoluminescence quantum yield and brightness of fluorescent particles in dispersion and as powders based on integrating sphere spectroscopy and underline the importance of such measurements for the understanding of the photophysics of such nanocrystals.
T2 - International Conference on Fundamental Processes in Semiconductor Nanocrystals (FQDots16)
CY - Berlin, Germany
DA - 05.09.2016
KW - Fluorescence
KW - Nanoparticle
KW - Semiconductor quantum dot
KW - Upconversion nanocrystal
KW - NIR
KW - Integrating sphere spectroscopy
KW - Fluorescence quantum yield
KW - Method
PY - 2016
AN - OPUS4-38695
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Resch-Genger, Ute
T1 - Effect of Particle Size and Excitation Power Density on the Luminescence Efficiency of Upconversion Nanocrystals in Different Dispersion Media
N2 - Upconversion nanoparticles (UCNPs) offer new strategies for luminescence-based sensing and imaging. One of the best studied materials are ..-NaYF4 UCNPs doped with 20 % Yb3+ and 2 % Er3+, which efficiently convert 976 nm light to photons emitted at 540 nm, 655 nm, and 845 nm, respectively, reveal long luminescence lifetimes (> 100 µs), are photostable and chemically inert. Their upconversion (UC) luminescence (UCL) properties are, however, strongly influenced by particle size, surface chemistry, and microenvironment. In addition, the multiphotonic absorption processes responsible for UCL render UCL excitation power density (..) dependent. This makes quantitative UCL measurements as well as the determination of UC quantum yields (.UC) very challenging.
The rational design of brighter UCNPs particle architectures and the interest in identifying optimum particle architectures for FRET-based sensing and imaging schemes, which often rely on core-only UCNPs to minimize donor-acceptor distances, encouraged us to assess the influence of particle size and P on UCL. Here, we present the photophysical properties of a series of hexagonal NaYF4 UCNPs with sizes from 10 to 43 nm with different surface ligands dispersed in organic solvents and water studied by steady state and time-resolved fluorometry as well as quantitatively by integrating sphere spectrometry with P varied over about three orders of magnitude. Our results underline the need for really quantitative luminescence studies for mechanistic insights and the potential of high P to compensate for UCL quenching due to high energy phonons and surface effects.
T2 - 15th Conference on Methods and Applications in Fluorescence
CY - Bruges, Belgium
DA - 10.09.2017
KW - Upconversion
KW - Nanoparticle
KW - Absolute fluorometry
KW - Integrating sphere spectroscopy
KW - NIR
KW - IR
KW - Fluorescence
KW - Surface chemistry
KW - Deactivation pathways
KW - Photophysics
KW - Quantum yield
PY - 2017
AN - OPUS4-43181
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Resch-Genger, Ute
A1 - Gorris, H.H.
T1 - Perspectives and challenges of photon-upconversion nanoparticles - Part I: routes to brighter particles and quantitative spectroscopic studies
N2 - Lanthanide-doped photon-upconversion nanoparticles (UCNPs) have been the Focus of many Research activities in materials and life sciences in the last 15 years because of their potential to convert light between different spectral regions and their unique photophysical properties. To fully exploit the application potential of These facinating nanomaterials, a number of challenges have to be overcome, such as the low brightness, particularly of small UCNPs, and the reliable quantification of the excitation-power-density-dependent upconversion luminescence. In this series of critical Reviews, recent developments in the design, Synthesis, optical-spectroscopic characterization, and application of UCNPs are presented with Special Focus on bioanalysis and the life sciences. Here we guide the reader from the Synthesis of UCNPs to different concepts to enhance their luminescence, including the required optical-spectroscopic assessment to quantify material Performance; surface modification strategies and bioanalytical applications as well as selected examples of the use of UCNPs as reporters in different Assay formats are addressed in part II. Future Trends and challenges in the field of upconversion are discussed with Special emphasis on UCNP Synthesis and material characterization, particularly quantitative luminescence studies.
KW - Fluorescence
KW - Lanthanide
KW - Upconversion
KW - Brightness
KW - Quantification
KW - Nanoparticle
KW - Absolute fluorometry
KW - NIR
KW - IR
KW - Quantum yield
PY - 2017
DO - https://doi.org/10.1007/s00216-017-0499-z
SN - 1618-2650
SN - 1618-2642
VL - 409
IS - 25
SP - 5855
EP - 5874
PB - Springer
AN - OPUS4-41665
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Zhao, J.
A1 - Hu, Y.
A1 - wei Lin, S.
A1 - Resch-Genger, Ute
A1 - Zhang, R.
A1 - Wen, J.
A1 - Kong, X.
A1 - Qin, A.
A1 - Ou, J.
T1 - Enhanced luminescence intensity of near-infraredsensitized sensitized upconversion nanoparticles via Ca²+ doping for a nitric oxide release platform
N2 - Light-induced NO release based on exogenous NO donors has attracted substantial attention in clinical applications; the induction light source usually converts near-infrared light to blue or ultraviolet light.
However, the low efficiency of near-infrared light-assisted chemical light energy conversion remains a challenge, especially for NaYF4:Yb3+/Tm3+ photoconverting near-infrared light to ultraviolet (UV) and blue light. In this paper, a luminescence-enhanced strategy is reported by doping Ca2+ into NaYF4:Yb3+/Tm3+ and coating it with NaGdF4 through a two-step solvothermal method. Then, UCNPs modified with methyl-b-cyclodextrin (M-b-CD) are loaded on a ruthenium nitrosyl complex [(3)Ru(NO)(Cl)] as nitric oxide release-molecules (NORMs). X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDS) data demonstrated that Ca2+ was successfully doped into NaYF4:Yb3+/Tm3+ nanoparticles as the core, and a pure hexagonal phase, NaYF4, was obtained from the doping of Ca2+. TEM revealed that the crystallinity was significantly improved after Ca2+ doping, and the core–shell structure was successfully synthesized, with NaGdF4 directionally grown on the NaYF4:Ca/Yb/Tm core. Fluorescence tests showed that, especially in the ultraviolet and blue light excitation wavelength regions, the UC emission intensity of the Ca-doped NaYF4:Yb3+/Tm3+@NaGdF4 core–shell UCNPs increased by 302.95 times vs. NaYF4:Yb3+/Tm3+ UCNPs. Finally, the release of NO was tested by the Griess method. Under 980 nm irradiation, the cell viability distinctly decreased with increasing UCNPs@M-b-CD-NORMs concentration. This study Shows that NORM release of NO is triggered by enhanced up-converted UV and blue light, which can be used for the development of UV photo-sensitive drugs.
KW - Nano
KW - Nanomaterial
KW - Upconversion nanoparticle
KW - Lanthanide
KW - Photoluminescence
KW - Quantum yield
KW - Photophysics
KW - Lifetime
KW - Sensor
KW - Surface chemistry
KW - Single particle
KW - Brightness
KW - NIR
KW - PDT
PY - 2020
DO - https://doi.org/10.1039/d0tb00088d
VL - 8
IS - 30
SP - 6481
EP - 6489
PB - Journal of Materials Chemistry B
AN - OPUS4-51262
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Frenzel, Florian
A1 - Würth, Christian
A1 - Dukhno, O.
A1 - Przybilla, F.
A1 - Wiesholler, L. M.
A1 - Muhr, V.
A1 - Horsch, T.
A1 - Mély, Y.
A1 - Resch-Genger, Ute
T1 - Multiband emission from single β-NaYF4(Yb,Er) nanoparticles at high excitation power densities and comparison to ensemble studies
N2 - Ensemble and single particle studies of the excitation power density (P)-dependent upconversion luminescence (UCL) of core and core–shell β-NaYF4:Yb,Er upconversion nanoparticles (UCNPs) doped with 20% Yb3+ and 1% or 3% Er3+ performed over a P regime of 6 orders of magnitude reveal an increasing contribution of the emission from high energy Er3+ levels at P > 1 kW/cm2.
This changes the overall emission color from initially green over yellow to white. While initially the green and with increasing P the red emission dominate in ensemble measurements at P < 1 kW/cm2, the increasing population of higher Er3+ energy levels by multiphotonic processes at higher P in single particle studies results in a multitude of emission bands in the ultraviolet/visible/near infrared (UV/vis/NIR) accompanied by a decreased contribution of the red luminescence. Based upon a thorough analysis of the P-dependence of UCL, the emission bands activated at high P were grouped and assigned to 2–3, 3–4, and 4 photonic processes involving energy transfer (ET), excited-state absorption (ESA), cross-relaxation (CR), back energy transfer (BET), and non-radiative relaxation processes (nRP). This underlines the P-tunability of UCNP brightness and color and highlights the potential of P-dependent measurements for mechanistic studies required to manifest the population pathways of the different Er3+ levels.
KW - Nano
KW - Nanomaterial
KW - Upconversion nanoparticle
KW - Lanthanide
KW - Photoluminescence
KW - Quantum yield
KW - Photophysics
KW - Llifetime
KW - Sensor
KW - Excitation power density
KW - Single particle
KW - Brightness
KW - NIR
KW - Mechanism
KW - Color tuning
PY - 2021
DO - https://doi.org/10.1007/s12274-021-3350-y
SN - 1998-0124
VL - 14
IS - 11
SP - 4107
EP - 4115
PB - Nano Research
AN - OPUS4-52364
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CHAP
A1 - Resch-Genger, Ute
ED - Schäferling, Michael
T1 - Luminescent nanoparticles for chemical sensing and imaging
N2 - The implementation of fluorescent methods is of outstanding importance in the field of optical chemical sensor Technology and biosciences. Their bioanalytical applications are manifold including fluorescence microscopy, fluorescence in situ hybridization, DNA sequencing, fluorescence-activated cell sorting, immunoassays, analysis of DNA and Protein microarrays, and quantitative PCR, just to name a few examples. Particularly, fluorescence microscopy is a valuable method in the versatile field of biomedical imaging methods which nowadays utilizes different fluorescence Parameters like emission wavelength/Color and lifetime for the discrimination between different targets. Sectional Images are available with confocal microscopes. Tissue, cells or single cellular compartments can be stained and visualized with fluorescent dyes and biomolecules can be selectively labeled with fluorescent dyes to Monitor biomolecular interactions inside cells or at Membrane bound receptors.
On the other hand , fluorophores can act as indicator (or "molecular probe") to visualize intrinsically colorless and non-fluorescent ionic and neutral analytes such as pH, Oxygen (pO2), metal ions, anions, hydrogen peroxide or bioactive small organic molecules such as Sugars or nucleotides. Thereby, their photoluminescent properties (fluorescence or phoporescence intensity, exitation and/or Emission wavelength, emission lifetime or anisotropy) respond to the presence of these species in their immediate Environment. In general, the use of luminescent probes has the advantage that they can be delivered directly into the sample, and detected in a contactless remote mode. By now, these probes are often encapsulated in different types of nanoparticles (NPs) made from (biodegradable) organic polymers, biopolymers or inorganic materials like silica or bound to their surface.
KW - Fluorescence
KW - Upconversion
KW - NIR
KW - Sensor
KW - Nanoparticle
KW - Surface chemistry
KW - Quantum yield
KW - Liftetime
KW - Nanocrystal
KW - Lanthanide
KW - Semiconductor
KW - Polymer
KW - Silica
KW - Imaging
KW - Application
KW - Dye
KW - Quantum dot
PY - 2017
SN - 978-3-319-48260-6
SN - 978-3-319-48259-0
DO - https://doi.org/10.1007/978-3-319-48260-6_5
SN - 1573-8086
SP - 71
EP - 109
PB - SPRINGER INTERNATIONAL PUBLISHING AG
CY - Cham, Schweiz
AN - OPUS4-44011
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Resch-Genger, Ute
T1 - Characterization of nanocrystalline particles with NIR emission - Spectroscopic properties and surface group analysis
N2 - There is an increasing interest in optical reporters like semiconductor quantum dots and upconversion nanocrystals with emission > 800 nm for bioanalysis, medical diagnostics, and safety barcodes. Prerequisites for the comparison of material performance, the mechanistic understanding of nonradiative decay channels, and the rational design of new nanomaterials with improved properties are reliable fluorescence measurements and validated methods for the assessment of their surface chemistry. The latter is of special relevance for nanocrystalline emitters, where surface states and the accessibility of emissive states by quenchers largely control accomplishable photoluminescence quantum yields and hence, signal sizes and detection sensitivities from the reporter side. Here, we present the design of integrating sphere setups for the excitation power density-dependent absolute measurement of emission spectra and photoluminescence quantum yields in the wavelength region of 350 to 1600 nm and results from spectroscopic studies of semiconductor quantum dots and upconversion nanocrystals of different size and surface chemistries in various environments. Subsequently, examples for simple approaches to surface group and ligand analysis are presented.
T2 - 1st International Biophotonics Conference
CY - Singapure
DA - 25.07.2016
KW - Fluorescence
KW - Integrating sphere spectroscopy
KW - Quantum yield
KW - NIR
KW - IR
KW - Optical spectroscopy
KW - Nanomaterials
KW - Semiconducor nanocrystals
KW - Surface analysis
KW - Ligand analysis
KW - Optical assay
PY - 2016
AN - OPUS4-36998
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Resch-Genger, Ute
T1 - Theory of the Photoluminescence Quantum Yield and its Measurement for Different Emitters
N2 - Mandatory for the comparison of different emitter classes and the rational design of the next generation of molecular and nanoscale reporters are reliable and quantitative photoluminescence measurements. This is of special relevance for all fluorescence applications in the life and material sciences. In the following, proccedures for the determination of this spectroscopic key parameter are presented including material-specific effects related to certain emitters
T2 - COST 2017
CY - Turku, Finland
DA - 03.04.2017
KW - Instrument calibration
KW - Standard
KW - Flourescence
KW - Reference material
KW - Absolute fluorometry
KW - Integrating sphere spectroscopy
KW - NIR
KW - IR
KW - Photophysics
KW - Quantum yield
KW - Dye
PY - 2017
AN - OPUS4-43175
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Resch-Genger, Ute
ED - Mousavi, M.
ED - Thomasson, B.
ED - Li, M.
ED - Kraft, Marco
ED - Würth, Christian
ED - Andersson-Engels, S.
T1 - Beam-profile-compensated quantum yield measurements of upconverting nanoparticles
N2 - The quantum yield is a critically important parameter in the development of lanthanide-based upconverting nanoparticles (UCNPs) for use as novel contrast agents in biological imaging and optical reporters in assays. The present work focuses on the influence of the beam Profile in measuring the quantum yield (f) of nonscattering dispersions of nonlinear upconverting probes, by establishing a relation between f and excitation light power density from a rate equation analysis. A resulting 60% correction in the measured f due to the beam profile utilized for excitation underlines the significance of the beam profile in such measurements, and its impact when comparing results from different Setups and groups across the world.
KW - Fluorescence
KW - Lanthanide
KW - Upconversion
KW - Brithtness
KW - Quantification
KW - Nanoparticle
KW - Absolute fluoreometry
KW - NIR
KW - IR
KW - Quantum yield
KW - Integrating sphere spectroscopy
KW - Method
PY - 2017
DO - https://doi.org/10.1039/c7cp03785f
SN - 1463-9076
SN - 1463-9084
VL - 19
IS - 33
SP - 22016
EP - 22022
PB - Royal Society of Chemistry
AN - OPUS4-42583
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Würth, Christian
T1 - New Trends in Fluorometry - Fluorescence Measurements above 1000 nm
N2 - Trends in fluorometry and fluorescence imaging are increasing applications of molecular and nanoscale reporters with emission > 800 nm and recently also > 1000 nm for bioanalysis, medical diagnostics, bioimaging, and safety barcodes. Mandatory for the comparison of different emitter classes and the rational design of the next generation of reporters for the short wavelength infrared (SWIR) region are reliable and quantitative photoluminescence measurements in this challenging wavelength region. This is of special relevance for nanocrystalline emitters like semiconductor quantum dots and rods as well as lanthanide-based upconversion and downconversion nanocrystals, where surface states and the accessibility of emissive states by quenchers largely control accomplishable photoluminescence quantum yields and hence, signal sizes and detection sensitivities from the reporter side. Such measurements are currently hampered by the lack of suitable methods and standards for instrument calibration and validation and quantum yield standards with emission > 800 nm and especially > 1000 nm.
In this respect, we present the design of integrating sphere setups for absolute and excitation power density-dependent measurements of emission spectra and photoluminescence quantum yields in the wavelength region of 650 to 1650 nm including calibration strategies and first candidates for potential fluorescence standards. Subsequently, selected examples for spectroscopic studies of different types of nanocrystals are presented including the upconversion and downconversion emission of differently sized and surface functionalized lanthanide-doped nanoparticles
T2 - COSP-Colloquium Optical Spectroscopy
CY - Berlin, Germany
DA - 27.11.2017
KW - Yield
KW - IR fluorescence
KW - Quantum dot
KW - Upconversion nanocrystal
KW - Lanthanide emitter
KW - NIR
KW - Integrating sphere spectroscopy
KW - Absolute fluorescence quantum
PY - 2017
AN - OPUS4-43327
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Osipova, Viktoriia
T1 - Incorporation of near-infrared light emitting chromium (III) complexes into silica nanoparticles and spectroscopic characterization
N2 - In recent years, chromium (III) complexes have received a lot of attention as novel near-infrared (NIR) emitters triggered by the report on the first molecular ruby Cr(ddpd)2(BF4)3 with a high photoluminescence quantum yield of 13.7% of its near infrared (NIR) emission band and a long luminescence lifetime of 1.122 ms at room temperature.[1] However, in an oxygen-containing environment, the photoluminescence quantum yields and luminescence lifetimes of these chromium(III) complexes show only very small values. This hampers their application as NIR luminescence labels. This application, that cannot be tackled by conventional deoxygenating approaches, requires suitable strategies to protect the luminescence of the chromium(III) complexes from oxygen quenching. An elegant approach to reduce the undesired luminescence quenching by triplet oxygen explored by us presents the incorporation of these chromium(III) complexes into different types of amorphous, non-porous silica nanoparticles, that can be simply surface functionalized, e.g., with targeting ligands and/or other sensor molecules. In this work, as first proof-of-concept experiments, a set of chromium (III) complexes constituting of different ligands and counter anions, were embedded into the core of silica nanoparticles. Subsequently, the optical properties of the resulting luminescent silica nanoparticles were spectroscopically assessed by steady state and time-resolved luminescence spectroscopy. First results of time-resolved luminescence measurements confirm our design concept of nanoscale NIR emissive Cr(III) complex-based reporters
T2 - Projekttreffen Nile-Chrome 2.0
CY - Mainz, Germany
DA - 11.12.2023
KW - Cr(III) complex
KW - NIR
KW - Luminescence
KW - Nano
KW - Silica
KW - Lifetime
KW - Quantum Yields
KW - Particle Synthesis
KW - Sensors
KW - Probe
KW - Surface Group Analysis
PY - 2023
AN - OPUS4-59149
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Resch-Genger, Ute
T1 - Semiconductor nanocrystals with VIS and NIR/IR emission - spectroscopy properties and surface chemistry
N2 - Semiconductor nanocrystals with a spherical (QDs) core and a spherical or a rod-shaped Shell, u.a., so-called Quantum dot-Quantum rods (QDQRs) are increasingly used as fluorescent Reporters or optically active components in the life and material science, e.g., in solid state lightening including Plasma Displays. (1,2) Morever, there is an increasing interest in materials with emission >800 nm for bioanalysis, medical diagnostics, and safety barcodes. Prerequisites for the mechanistic understanding of nonradiativ decay channels needed for the rational design of improved nanomaterials and the comparison of material Performance are reliable fluorescence measurements and validated methods for the assessment of their surface chemistry. (3,4) The latter is of particular importance for nanocrystalline Emitters, where surface states and the accessibility of emissive states by quenchers largely control photoluminescence properties. (5) Here, we present results from systematic spectroscopic studies including absolutely measured photolumunescence Quantum yields of different vissible and NIR emisisve QD and QDQRs Systems of varying particle architecture size and surface chemistries in Dispersion and embedded in salt crystals. (6,7)
T2 - MCare 2017
CY - Jeju, South Korea
DA - 20.02.2017
KW - Semiconductor quantum dot
KW - Nanoparticle
KW - Absolute fluorometry
KW - Integrating sphere spectroscopy
KW - NIR
KW - IR
KW - Fluorescence
KW - Surface chemistry
KW - Photophysics
KW - Quantum yield
KW - Single particle
PY - 2017
AN - OPUS4-43133
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Huang, K.
A1 - Liu, H.
A1 - Kraft, Marco
A1 - Shikha, S.
A1 - Zheng, X.
A1 - Agren, H.
A1 - Würth, Christian
A1 - Resch-Genger, Ute
A1 - Zhang, Y.
T1 - A protected excitation-energy reservoir for efficient upconversion luminescence
N2 - Lanthanide-doped upconversion nanoparticles (UCNPs) are of great interest for biomedical applications. Currently, the applicability of UCNP bionanotechnology is hampered by the generally low luminescence intensity of UCNPs and inefficient energy Transfer from UCNPs to surface-bound chromophores used e.g. for photodynamic therapy or analyte sensing. In this work, we address the low-Efficiency issue by developing versatile core-Shell nanostructures, where high-concentration sensitizers and activators are confined in the core and Shell Region of representative hexagonal NaYF2:Yb,Er UCNPs. After Doping concentration optimization, the sensitizer-rich core is able to harvest/accumulate more excitation energy and generate almost one order of Magnitude higher luminescence intesity than conventional homogeneously doped nanostructures. At the same time, the activator Ions located in the Shell enable a ~6 times more efficient resonant energy Transfer from UCNPs to surface-bound acceptor dye molecules due to the short distance between donor-acceptor pairs. Our work provides new insights into the rational design of UCNPs and will greatly encrease the General applicability of upconversion nanotechnologies.
KW - Fluorescence
KW - Lanthanide
KW - Upconversion
KW - Brightness
KW - Quantification
KW - Nanoparticle
KW - Absolute fluorometry
KW - NIR
KW - IR
KW - Quantum yield
KW - Integrating sphere spectroscopy
KW - Method
KW - Energy transfer
KW - Shell
KW - Particle architecture
PY - 2017
DO - https://doi.org/10.1039/c7nr06900f
SN - 2040-3372
SN - 2040-3364
VL - 10
IS - 1
SP - 250
EP - 259
PB - The Royal Society of Chemistry
AN - OPUS4-43893
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Resch-Genger, Ute
T1 - Quantitative Characterization of Functional Nanomaterials with vis/NIR Emission
N2 - The rational design of functional nanomaterials for optical applications in the material and life sciences requires optical-spectroscopic methods for the quantitative characterization of their signal-relevant optical properties. Additionally, methods for the simple and quantitative analysis of the surface chemistry are desired as the chemical nature and number of the surface groups and ligands can affect the optical features and controls the interaction of these nanomaterials with their environment. Here, we present quantitative photoluminescenvce studies of different types of vis/NIR-emissive nanomaterials like semiconductor quantum dots and upconversion nanocrystals will be presented and their relevance for the mechanistic understanding of nonradiative decay channels and the rational design of new nanomaterials will be underpinned. In this respect, also validation concepts for such measurements and absolute fluorometry will be introduced. In addition, the potential of optical spectroscopy for surface group and ligand analysis surface chemistry will be demonstrated exemplarily for semiconductor quantum dots
T2 - AK Prof. Voss
CY - Uni Brunswick, Germany
DA - 03.08.2017
KW - Semiconductor
KW - Upconversion
KW - Nanoparticle
KW - Fluorescence
KW - Surface group analysis
KW - NIR
KW - Absolute fluoreometry
KW - Integrating sphare spectroscopy
KW - Optical probe
KW - Assay
KW - Thiol ligand
PY - 2017
N1 - Geburtsname von Nirmalananthan-Budau, Nithiya: Nirmalananthan, N. - Birth name of Nirmalananthan-Budau, Nithiya: Nirmalananthan, N.
AN - OPUS4-41366
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Resch-Genger, Ute
T1 - Challenges and examples for quantitative fluorescence measurements > 800 nm with semiconductor and lanthanide-doped nanocrystals
N2 - There is an increasing interest in molecular and nanoscale with emission > 800 nm and recently also > 1000 nm for bioanalysis, medical diagnostics, bioimaging, and safety barcodes. Mandatory for the comparison of different emitter classes and the rational design of the next generation of reporters for the short wavelength infrared (SWIR) Region are reliable and quantitative photoluminescence measurements in this challenging wavelength region. This is of special relevance for nanocrystalline emitters like semiconductor quantum dots and rods as well as lanthanide-based upconversion and downconversion nanocrystals, where surface states and the accessibility of emissive states by quenchers largely control accomplishable photoluminescence quantum yields and hence, signal sizes and detection sensitivities from the reporter side. Such measurements are currently hampered by the lack of suitable methods and standards for instrument calibration and validation and quantum yield standards with emission > 800 nm and especially > 1000 nm.
In this respect, we present the design of integrating sphere setups for absolute and excitation power density-dependent measurements of emission spectra and photoluminescence quantum yields in the wavelength Region of 650 to 1650 nm including calibration strategies and first candidates for potential fluorescence standards.
Subsequently, the photoluminescence properties of different types of nanocrystals are presented including the upconversion and downconversion emission of differently sized and surface functionalized lanthanide-doped nanoparticles and photoluminescence quenching effects are quantified.
T2 - SHIFT 2017
CY - Teneriffa, Spain
DA - 13.11.2017
KW - Upconversion
KW - Nanoparticle
KW - Absolute fluorometry
KW - Integrating sphere spectroscopy
KW - NIR
KW - IR
KW - Fluorescence
KW - Surface chemistry
KW - Deactivation pathways
KW - Semiconductor quantum dot
KW - SWIR
KW - Quantum yield
PY - 2017
AN - OPUS4-43203
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Resch-Genger, Ute
T1 - Spectroscopic characterization of semiconductor and lanthanide-based nanocrystals with vis and NIR emission
N2 - The increasing interest in molecular and nanoscale emitters with photoluminescence > 800 nm and recently also > 1000 nm for bioanalysis, medical diagnostics, bioimaging, and safety Barcodes requires quantitative spectroscopic studies, which are, however still challenging in this long wavelength region. This is of special relevance for nanocrystalline emitters like semiconductor quantum dots and rods as well as lanthanide-based upconversion and downconversion nanocrystals, where surface states and the accessibility of emissive states by quenchers largely control accomplishable photoluminescence quantum yields and hence, signal sizes and detection sensitivities from the reporter side. Moreover, nonlinear emitters like lanthanide-based upconversion nanocrystals require also power density-dependent studies of their luminescence spectra, quantum yields, and decay kinetics. Here, we present suitable absolute methods and underline the impact of such measurements on a profound mechanistic understanding of the nonradiative deactivation pathways in semiconductor and upconversion nanocrystals of different chemical composition and particle architecture.
T2 - PCNSPA 2018 - Photonic Colloidal Nanostructures: Synthesis, Properties, and Applications
CY - St. Petersburg, Russia
DA - 04.06.2018
KW - Semiconductor
KW - Nanoparticle
KW - Quantum dot
KW - Absolute fluorometry
KW - Integrating sphere spectroscopy
KW - NIR
KW - IR
KW - Fluorescence
KW - Surface chemistry
KW - Deactivation pathways
KW - Photophysics
KW - Modeling
PY - 2018
AN - OPUS4-45796
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Resch-Genger, Ute
T1 - The European Upconversion Network: From the Design of Photon-upconverting Nanomaterials to (Biomedical) Applications (CM1403) WG1 Materials Research & Photophysical Characterization
N2 - Lanthanide-doped photon-upconversion nanoparticles (UCNPs) have been in the focus of many research activities in the material and life sciences over the last 15 years because of their potential to convert light between different spectral regions and their unique photophysical properties. In order to fully exploit the application potential of these fascinating nanomaterials, a number of challenges has to be overcome such as the low brightness particularly of small UCNPs and the reliable quantification of the excitation power density (P)-dependent upconversion luminescence (UCL). Here, the need and requirements on the characterization of the optical properties of UCNPs are discussed with special focus on the reliabiliy and comparability of relative and quantitative luminescence measurements and prerequisites for their standardization.
T2 - COST Treffen
CY - Aveiro, Portugal
DA - 26.06.2017
KW - Upconversion
KW - Nanoparticle
KW - Fluorescence
KW - NIR
KW - Absolute fluorometry
KW - Integrating sphere spectroscopy
KW - Reference maerial
KW - Standardization
KW - Quantum yield
PY - 2017
AN - OPUS4-41367
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Resch-Genger, Ute
A1 - Pauli, J.
A1 - Güttler, Arne
A1 - Richter, Maria
A1 - Fiedler, Saskia
A1 - Frenzel, Florian
A1 - Wegner, Karl David
A1 - Würth, Christian
T1 - Photoluminescence Quantum Yields of Luminescent Nanocrystals and Particles in the UV/vis/NIR/SWIR
N2 - The rational design of functional luminescent materials such as semiconductor quantum dots and lanthanide-based upconversion nanoparticles, all photophysical and mechanistic studies, and the comparison of different emitters require accurate and quantitative photoluminescence measurements. Particularly the reliable determination of the key performance parameter photoluminescence quantum yield (f), the number of emitted per absorbed photons, and the brightness are of special importance for luminescence applications in the life and material sciences and nano(bio)photonics.[1] In this context, examples for absolute measurements of the photoluminescence quantum yields of UV/vis/NIR/SWIR emissive semiconductor quantum dots and rods, made from different materials, and spectrally shifting lanthanide upconversion nanocrystals with different surface chemistries in transparent matrices are presented including excitation wavelength and power density dependent studies utilizing integration sphere spectroscopy.[2,3] In addition, procedures for the absolute determination of the photoluminescence quantum yields of scattering dispersions of larger size quantum rods and differently sized inorganic particles have been developed as well as procedures for the characterization of solid luminescent nanomaterials such as different perovskites and YAG:Cer converter materials.[4] Thereby, challenges and pitfalls of f measurements in different wavelength regions including the SWIR and material-specific effects related to certain emitter classes are addressed, achievable uncertainties are quantified, and relative and absolute measurements of photoluminescence quantum yield measurements are compared to underline limitations of the former approach. Finally, a set of novel UV/vis/NIR quantum yield standards is presented including their certification with a complete uncertainty budget.[5]
T2 - NANAX 10
CY - Klosterneuburg, Austria
DA - 03.07.2023
KW - Fluorescence
KW - Optical spectroscopy
KW - Reference data
KW - Traceability
KW - NIR
KW - Scattering
KW - Reference material
KW - Certification
KW - Quality assurance
KW - Dye
KW - Reference product
KW - SWIR
KW - Nano
KW - Particle
KW - Perovskite
KW - Integrating sphere spectroscopy
KW - Quantum yield
PY - 2023
AN - OPUS4-58238
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Resch-Genger, Ute
T1 - Instrument Calibration and Standardization of Fluorescence Measurements in the UV/vis/NIR/IR
N2 - Comparison of fluorescence measurements performed on different fluorescence instruments, analyte quantification from fluorescence intensities as well as the determination of fluorescence quantum yields require instrument calibration and consideration of the wavelength-dependent instrument-specific quantities spectral photon flux reaching the sample and spectral responsivity. Here, we present guidelines and recommendations for the qualification of fluorescence instruments and introduce suitable chromophore-based reference materials. Moreover, the design concepts of the different BAM fluorescence standards are discussed.
T2 - COST 2017
CY - Turku, Finland
DA - 03.04.2017
KW - Fluorescence
KW - Dye
KW - Glass
KW - Calibration
KW - Fluorescence standard
KW - Integrating sphere spectroscopy
KW - Fluorescence quantum yield
KW - Instrument qualification
KW - Quality assurance
KW - NIR
KW - IR
PY - 2017
AN - OPUS4-43174
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Frenzel, Florian
T1 - Power dependent optical properties of hexagonal β-NaYF4: x % Er3+, 20 % Yb3+ core/ core-shell upconversion nanoparticles in cyclohexane and water
N2 - Lanthanide doped photon upconverting nanophosphors (UCNPs) have the unique capability to produce narrow band, multi-color emission in the UV/vis/NIR upon multiphotonic absorption of infrared light, which makes them promising reporters for diagnostic, bioanalytical, and biological applications. This minimizes background signals, which normally occur due to autofluorescence from auxochromes, in biological matrices and enables deep penetration depths in biological applications. Moreover, UCNPs show long luminescence lifetimes in the μs range favorable for time gated emission in conjunction with a high photostability and chemical inertness and they do not blink. One of the most efficient upconversion (UC) phosphors for conversion of 976 nm to 655 nm and 545 nm light presents the hexagonal NaYF4-host crystal doped with 20 % Yb3+ used as sensitizer to absorb infrared light and 2 % Er3+ acting as activator mainly responsible for light emission. The high transparency in the relevant spectral windows of this host together with its low phonon frequencies ensure relatively high luminescence efficiencies.
Although UCNPs are ideal candidates for many chemical and biological sensing and imaging applications, compared to other well-known chromophores like organic dyes or QDs, they suffer from a comparatively low brightness due to the low absorption cross sections of the parity forbidden f-f-transitions and low photoluminescence quantum yields (QYUC) particularly in the case of small nanoparticles with sizes of < 50 nm. The rational design of more efficient UCNPs requires an improved understanding of the nonradiative decay pathways in these materials that are influenced by particle architecture including dopant ion concentration and homogeneity of dopant distribution within UCNPs, size/surface-to-volume ratio, surface chemistry, and microenvironment. A promising approach to overcome the low efficiency of UCNPs is to use plasmonic interactions between a noble metal (Ag or Au) structure in the proximity of UCNPs and the incident light. This interaction leads to a modification of the spectroscopic properties due
to local field enhancements and can involve an increase of the photoluminescence. In this respect, we study the interactions of UCNPs with metal structures (clusters and shells) by varying shape and size. Here, first results derived from integrating sphere spectroscopy and time-resolved fluorescence measurements are presented.
T2 - Summer School "EXCITING NANOSTRUCTURES"
CY - Bad Honnef, Germany
DA - 17.07.2017
KW - Upconversion
KW - Nanoparticle
KW - Flourescence
KW - Core-shell architecture
KW - NIR
KW - Absolute flourometry
KW - Integrating sphere spectroscopy
KW - Er(III)
KW - Yb(III)
KW - Single particle spectroscopy
PY - 2017
AN - OPUS4-41172
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -