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 - Petrov, Eugene A1 - Würth, Christian A1 - Richter, Maria A1 - Resch-Genger, Ute T1 - Fluorescence Standards from BAM - Dye Solutions and Polymer systems N2 - For fluorescence microscopy, there is an increasing need for suitable calibration tools and reference materials for microscope calibration, the determination of performance parameters, and the regular control and validation of instrument performance. This is addressed in the BmWk-financed project FluMikal (WIPANO program) by two research groups from academia and two companies, that is coordinated by BAM. Here we present different approaches to liquid and solid fluorescence standards for the determination of the wavelength-dependent spectral sensitivity of fluorescence microscopes and ideas concerning the choice of suitable fluorescence lifetime standard for increasingly utilized fluorescence lifetime imaging (FLIM). T2 - FluMiKal Projectmeeting CY - Munich, Germany DA - 27.11.2023 KW - Reference material KW - Reference product KW - Fluorescence microscopy KW - Quality assurance KW - Instrument performance validation KW - Lifetime standard PY - 2023 AN - OPUS4-59120 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 - Resch-Genger, Ute A1 - Würth, Christian A1 - Pauli, Jutta A1 - Weigert, Florian T1 - Quantitative optical-spectroscopic characterization of luminescent nanomaterials - Photoluminescence Quantum Yields N2 - Accurate and quantitative photoluminescence measurements are mandatory for the comparison of different emitter classes and the rational design of the next generation of molecular and nanoscale reporters as well as for most applications relying on their luminescence features in the life and material sciences and nanobiophotonics. In the following, procedures for the determination of the spectroscopic key parameter photoluminescence quantum yield, i.e., the number of emitted per absorbed photons, in the UV/vis/NIR/SWIR are presented including pitfalls and achievable uncertainties and material-specific effects related to certain emitter classes are addressed. Special emphasis is dedicated to luminescent nanocrystals. T2 - International Workshop on "Emerging Nanomaterials for Displays and SSL" CY - Dresden, Germany DA - 11.11.2021 KW - Nano KW - Nanomaterial KW - Nanocrystal KW - Semiconductor quantum dot KW - Lanthanide KW - Photoluminescence KW - Quantum yield KW - Photophysics KW - Lifetime KW - Surface chemistry KW - Brightness KW - NIR KW - SWIR KW - Method KW - Uncertainty KW - Rreference material PY - 2021 AN - OPUS4-53783 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Würth, Christian T1 - Spektroskopie mit der Ulbrichtkugel: Streuende und floureszierende Systeme in der Bioanalytik T2 - PTB-Institutsseminar T2 - PTB-Institutsseminar CY - Braunschweig, Germany DA - 2013-01-23 PY - 2013 AN - OPUS4-27806 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Würth, Christian A1 - Resch-Genger, Ute A1 - Behnke, Thomas A1 - Pauli, Jutta A1 - Hennig, Andreas A1 - Hoffmann, Angelika A1 - Hoffmann, Katrin A1 - Hatami, Soheil A1 - Spieles, Monika T1 - Functional Chromophores and Optical Spectroscopy in Bioanalysis T2 - PTB Braunschweig im FB 4.1 T2 - PTB Braunschweig im FB 4.1 CY - Braunschweig, Germany DA - 2013-01-23 PY - 2013 AN - OPUS4-29234 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Würth, Christian A1 - Behnke, Thomas A1 - Pauli, Jutta A1 - Hennig, Andreas A1 - Hoffmann, Katrin A1 - Hoffmann, Angelika A1 - Hatami, Soheil A1 - Spieles, Monika A1 - Resch-Genger, Ute T1 - Functional Chromophores for Bioanalysis and Material Sciences Based on Molecular Fluorophores and Differently Sized Beads T2 - Institut für Mikrotechnik Mainz (IMM) T2 - Institut für Mikrotechnik Mainz (IMM) CY - Mainz, Germany DA - 2013-02-19 PY - 2013 AN - OPUS4-29235 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Würth, Christian A1 - Resch-Genger, Ute T1 - Determination of Quantum Yiels and Efficiencies of Fluorescent Particles with an Integrating Sphere Setup T2 - MAF 13 T2 - MAF 13 CY - Genoa, Italy DA - 2013-09-08 PY - 2013 AN - OPUS4-29574 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Würth, Christian A1 - Grabolle, Markus A1 - Pauli, Jutta A1 - Spieles, Monika A1 - Resch-Genger, Ute T1 - Relative und absolute Messungen der Photolumineszenzquantenausbeute (?f) und erreichbare Unsicherheiten T2 - VDI-Fachtagung Messunsicherheit 2013 T2 - VDI-Fachtagung Messunsicherheit 2013 CY - Braunschweig, Germany DA - 2013-11-05 PY - 2013 AN - OPUS4-29575 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Würth, Christian A1 - Resch-Genger, Ute T1 - Luminescence characterization with an integrating sphere T2 - Chebana - Upcare Joint Seminar T2 - Chebana - Upcare Joint Seminar CY - Regensburg, Germany DA - 2012-08-30 PY - 2012 AN - OPUS4-27069 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Würth, Christian T1 - Relative and absolute determination of the quantum efficiency of transparent and scattering luminescent materials T2 - Institutsseminar Werkstoffwissenschaften Universität Erlangen T2 - Institutsseminar Werkstoffwissenschaften Universität Erlangen CY - Erlangen, Germany DA - 2014-06-23 PY - 2014 AN - OPUS4-30919 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Würth, Christian A1 - Hatami, Soheil A1 - Kaiser, Martin A1 - Pauli, Jutta A1 - Resch-Genger, Ute T1 - Absolute fluorescence measurements > 1000 nm: setup design, calibration and standards N2 - Bright emitters with photoluminescence in the spectral region of 800 – 1600 nm are increasingly important as optical reporters for molecular imaging, sensing, and telecommunication and as active components in electrooptical and photovoltaic devices. Their rational design is directly linked to suitable methods for the characterization of their signal-relevant properties, especially their photoluminescence quantum yield. Aiming at the development of bright semiconductor nanocrystals with emission > 1000 nm, we designed a new NIR/IR integrating sphere setup for the wavelength region of 600 – 1600 nm. We assessed the performance of this setup by acquiring the corrected emission spectra and quantum yield of the organic dyes Itrybe, IR140, and IR26 and several infrared (IR)-emissive Cd1-xHgxTe and PbS semiconductor nanocrystals and comparing them to data obtained with two independently calibrated fluorescence instruments absolutely or relatively to previously evaluated reference dyes. Our results highlight special challenges of photoluminescence studies in the IR ranging from solvent absorption to the lack of spectral and intensity standards together with quantum dot-specific challenges like photobrightening and photodarkening and the size-dependent air stability and photostability of differently sized oleate-capped PbS colloids. These effects can be representative for lead chalcogenides. Moreover, we redetermined the quantum yield of IR26, the most frequently used IR reference dye, to 1.1×10-3 in 1,2-dichloroethane DCE with a thorough sample reabsorption and solvent absorption correction. T2 - SPIE CY - San Francisco, USA DA - 11.02.2016 KW - Ir KW - Quantum yield PY - 2016 AN - OPUS4-38405 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Würth, Christian A1 - Kaiser, Martin A1 - Kraft, Marco A1 - Muhr, Verena A1 - Wilhelm, Stefan A1 - Hirsch, Thomas A1 - Resch-Genger, Ute T1 - Setup for the power-dependent absolute quantum yield measurements of luminescent reporters in the VIS and IR spectral region: example of upconversion nanoparticles N2 - The design of bright of upconversion nanoparticles requires an improved understanding of the radiationless deactivation pathways in UCNP, that are affected by their size1,2, surface chemistry,2 and microenvironment 3,4. In this respect, we discuss experimental requirements of an integrating sphere setup for absolute measurements of the excitation power density dependent quantum yield5,6 (UC(P)) in the VIS to IR spectral region. We report systematic studies of the influence of the UCNP size, surface ligands, and solvent on the UC(P), the up- and downconversion luminescence decay behavior, the power dependent intensities of the individual emission bands, and their slope factors. T2 - SPIE Photonics West CY - San Francisco, USA DA - 11.02.2016 KW - Upconversion KW - Quantum Yield PY - 2016 AN - OPUS4-38406 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Würth, Christian A1 - Kaiser, Martin A1 - Kraft, Marco A1 - Muhr, Verena A1 - Wilhelm, Stefan A1 - Hirsch, Thomas A1 - Resch-Genger, Ute T1 - Setup for the power-dependent absolute quantum yield measurements: example of upconversion nanoparticles N2 - Lanthanide-doped up-converting nanoparticles (UCNPs), are promising reporters for bioanalysis and theranostics, which are excitable in the near infrared (NIR) by multiphoton absorption processes, and show multiple narrow emission bands in the visible (vis) and NIR, excellent photostability, and long luminescence lifetimes in the µs range. The rational design of brighter UCNP requires an improved understanding of the radiationless deactivation pathways in UCNP, that are affected by size, surface chemistry, and microenvironment. In this respect, we discuss the experimental requirements on absolute measurements of the upconversion quantum yield and its excitation radiant power density dependence and present the design and characterization of unique integrating sphere setup for such measurements in the vis to IR spectral region including its calibration, the influence of the excitation beam profile and solutions to perform such measurements in aqueous media. T2 - Upcon2016 CY - Breslau, Poland DA - 23.05.2016 KW - Upconversion KW - Quantum yield KW - Nanoparticle PY - 2016 AN - OPUS4-38409 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Würth, Christian A1 - Resch-Genger, Ute A1 - Fischer, Stefan A1 - Hirsch, Thomas T1 - Systematic characterization of Upconversion nanoparticles: Effect of size, microenvironment, Energy transfer, shells N2 - Solid state multi-band emitters like lanthanide doped up-conversion nanoparticles (UCNPs) are promising materials for energy and biotechnologies. These materials are excitable in the near infrared (NIR) and show emission bands from UV to SWIR with excellent photostability, and long luminescence lifetimes in the µs range. The efficiency of these materials, i.e. the multiphoton absorption processes, the excitation power dependent population, and deactivation dynamics are strongly influenced by the particle size, structure, doping concentration, surface chemistry, and microenvironment. For applications UCNPs have to be optimized to meet the application relevant optical properties like the upconversion quantum yield (UC) and downshifting quantum yield (PL), luminescence lifetime and emission spectra. We investigated ß-NaYF4 NPs co-doped with Yb3+ and Er3+ in aqueous and organic media and as powder. For the later, bulk and nanomaterial is compared. For dispersed particles the influence of surface chemistry (ligands), microenvironment (solvent) and size (10 to 43 nm) was studied. Especially for bioapplications the Förster-Resonance-Energy-Transfer (FRET) efficiency from UCNPs to organic dye molecules (rose bengal and sulforhodamine B) was optimized with respect to the UCNP size. T2 - UpCon 2018 CY - Valencia, Spanien DA - 02.04.2018 KW - Nanoparticle KW - Upconversion KW - Quenching PY - 2018 AN - OPUS4-44762 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Würth, Christian A1 - Kaiser, Martin A1 - Resch-Genger, Ute 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 - Würth, Christian A1 - Kaiser, M. A1 - Levchuk, I. A1 - Batentschuk, M. A1 - Hirsch, T. A1 - Resch-Genger, Ute T1 - Absolute quantum yield measurements of spectral conversion materials - Instrumentation and applications N2 - The direct measure for the conversion efficiency of absorbed photons into emitted light by an emissive species or chromophore is the photoluminescence quantum yield (pl).1 pl is the fluorometric key quantity that controls the suitability of a molecule or material e.g. for application as a label, probe or sensor molecule or as a converter material. A straightforward approach to pl values presents their absolute determination using an integrating sphere set up. This procedure circumvents the use of standards thereby avoiding additional measurements and uncertainties related to their often debated pl values. In this respect, we discuss the experimental requirements on absolute measurements of down and upconversion quantum yields (UC), the later presents currently one of the most challenging spectroscopic measurements due to its multiphotonic character. We explore the challenges for determination of excitation power density (P) dependent pl(P), present the design and characterization of a unique integrating sphere setup for such measurements in the vis to IR spectral region including its calibration, and the influence of the excitation beam profile to perform pl measurements of liquid and solid materials. As an example for downshifting materials we present doped core-shell CdSe/ZnS semiconductor quantum dots (d-dots) which show a nearly host material and crystal size independent emission with large Stokes shifts and minimum reabsorption.2 Systematic variation of the reaction components, parameters and thickness of the ZnS shell yielded doped nanocrystals with a very high pl, high reproducibility and large quantities. Application of these NCs in the light conversion layers of commercial monocrystalline silicon (mono-Si) solar cells led to a significant enhancement of the external quantum efficiency (EQE) of this devices in the ultraviolet spectral region between 300 and 400 nm. On the other hand, lanthanide-doped up-converting nanoparticles (UCNPs), are promising light converters from the near infrared to the visible region. These NPs show multiple narrow emission bands in the visible (vis) and NIR, excellent photostability, and long luminescence lifetimes. The rational design of brighter UCNP requires an improved understanding of the radiationless deactivation pathways, that are affected by size, surface chemistry, and microenvironment.3 We give an insight into the influences of these parameters on the photophysical key characteristics of the upconversion process such as UC(P), the luminescence decay behavior, the power dependent red-to-green intensity ratio, and intensities of the individual emission bands. T2 - MCare-Materials Challenges in Alternative and Renewable Energy CY - Jeju, Korea DA - 20.02.2017 KW - Energy conversion KW - Quantum yield KW - Doped quantum dots KW - Upconversion PY - 2017 AN - OPUS4-40009 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Würth, Christian T1 - Scattering of Particles N2 - Introduction to theory and applications of light scattering T2 - Cost-action Training school CY - Turku, Finland DA - 03.04.2017 KW - Light scattering PY - 2017 AN - OPUS4-40010 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Würth, Christian A1 - Kaiser, M. A1 - Resch-Genger, Ute T1 - Theory of quantum yields - Excitation power dependent measurements N2 - Introduction to power dependent QY-measurements and upconversion T2 - Cost-action Training school CY - Turku, Finland DA - 03.04.2017 KW - Quantum yield KW - Upconversion PY - 2017 AN - OPUS4-40011 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Würth, Christian T1 - Time resolved spectroscopy of upconverting lanthanide based upconversion nanocrystals N2 - The optical properties of these materials strongly depend on the excitation power density, i.e., the number of photons absorbed per time interval. The upconversion quantum efficiencies (ΦUC) of these materials, the excitation power dependent population i.e. the emission characteristics, and the deactivation dynamics are influenced by nanoparticle architecture, doping concentration, and the microenvironment. We will discuss how time resolved measurements can help to understand the fundamental photophysical mechanisms and discuss differences to other nanocrystals like quantum dots. T2 - 19th International Course on “Principles and Applications of Time-resolved Fluorescence Spectroscopy” CY - Berlin, Germany DA - 16.11.2022 KW - Nanoparticle KW - Lanthanide KW - Upconversion KW - Energy transfer PY - 2022 AN - OPUS4-57000 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -