TY - CONF A1 - Resch-Genger, Ute A1 - Hatami, Soheil A1 - Würth, Christian A1 - Kaiser, Martin A1 - Leubner, S. A1 - Gaponik, N. A1 - Eychmüller, A. T1 - Absolute fluorescence measurements > 1000 nm - Setup design, calibration and standards N2 - There is an increasing interest in optical reporters like semiconductor quantum dots and upconversion nanophosphors with emission > 1000 nm for bioanalysis, medical diagnostics, and safety barcodes and hence, in reliable fluorescence measurements in this wavelength region, e.g., for the comparison of material performance and the rational design of new nanomaterials with improved properties. Here, we present the design of an integrating sphere setup for the absolute measurement of emission spectra and quantum yields in the wavelength region of 650 to 1600 nm and its calibration as well as examples for potential fluorescence standards from different reporter classes for the control of the reliability of such measurements. T2 - SPIE Photonics West 2016 CY - San Francisco, CA, USA DA - 15.02.2016 KW - IR fluorescence KW - Quantum dot KW - Upconversion nanocrystal KW - Integrating sphere spectroscopy KW - Absolute fluorescence quantum yield KW - Nanophosphor KW - Calibration PY - 2016 AN - OPUS4-35953 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 - Grauel, Bettina A1 - Nirmalananthan-Budau, Nithiya A1 - Pauli, Jutta A1 - Hoffmann, Katrin T1 - Photoluminescence at BAM – Photoluminescence at BAM – Photophysical Studies, Quantum Yield Measurements, Multiplexing Strategies, and Standards N2 - Photoluminescence applications in the life and material sciences require bright molecular and nanocrystalline emitters, stimuli-responsive optical probes, signal enhancement, multiplexing, and barcoding strategies and traceable methods to quantify the signal-relevant optical properties of luminescent materials at the ensemble and single molecule/particle level. In this context, current research at Division Biophotonics of BAM is presented ranging from dye and nanocrystal photophysics, absolute measurements of photoluminescence quantum yields in the UV/vis/NIR/SWIR, lifetime multiplexing, and the development of different types of fluorescence standards for validating optical-spectroscopic measurements. T2 - Institutskolloquium IPHT CY - Jena, Germany DA - 22.10.2019 KW - Surface group analysis KW - NIR KW - SWIR KW - Quantum dot KW - Lanthanide KW - Cleavable probe KW - Lifetime KW - Multiplexing KW - Sensor KW - Assay PY - 2019 AN - OPUS4-49360 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Resch-Genger, Ute T1 - Advanced characterization of nanomaterials N2 - The rational synthesis and use of nanomaterials require the characterization of many different properties, ranging from particle size and size distribution over surface chemistry to more applicationrelevant features like optical, electrochemical, and magnetic properties. In the following, several methods for the characterization of functional groups on nanomaterials, like polymer and silica nanoparticles, semiconductor quantum dots, and lanthanide-based upconversion nanocrystals are presented. Additionally, procedures for the measurement of the key spectroscopic performance parameters of nanomaterials with linear and nonlinear photoluminescence, such as the photoluminescence quantum yield, are presented for the UV/vis/NIR/SWIR. T2 - Summerschool CY - Bad Honnef, Germany DA - 22.07.2019 KW - Quantum yield KW - Nanoparticle KW - Fluorescence KW - Quantum dot KW - NIR KW - SWIR KW - Quality assurance KW - Calibration PY - 2019 AN - OPUS4-48630 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Resch-Genger, Ute A1 - Pauli, Jutta A1 - Würth, Christian A1 - Güttler, Arne A1 - Richter, Maria A1 - Schneider, Thomas T1 - Determining Photoluminescence Quantum Yields of Molecular and Nanocrystal Emitters in the UV/vis/NIR/SWIR N2 - The comparison of different emitter classes and the rational design of the next generation of molecular and nanoscale reporters require accurate and quantitative photo-luminescence measurements. This is of special importance for all photoluminescence applications 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. T2 - Kolloqium National Center for Nanoscience and Technology CY - Peking, People's Republic of China DA - 18.10.2019 KW - Fluorescence KW - Quantum yield KW - Integrating sphere spectroscopy KW - Dye KW - Nanocrystal KW - NIR KW - SWIR KW - Quantum dot KW - Fluorescence standard KW - Uncertainty KW - Calibration PY - 2019 AN - OPUS4-49362 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hübner, Oskar A1 - Resch-Genger, Ute T1 - Spectral and Lifetime Encoding of Polymer Particles with Cd-free Ternary Semiconductor Nanocrystals for Flow Cytometry with Time Resolved Fluorescence Detection N2 - Multiplexed encoding schemes of nano- and micrometer sized particles with fluorescent dyes or quantum dots (QDs) and their optical detection, are of increasing interest for applications in the life sciences, for example in flow cytometry. Almost all strategies utilizing fluorescence focus on spectrally distinguishable emission bands or colors and different intensity levels as fluorescence codes. The fluorescence parameter lifetime has been, however, barely exploited. In this work the goal is to perform multiplexing with encoding fluorophores with different fluorescence lifetimes (LTs). In comparison to the spectral multiplexing strategies this has the advantage, that the different fluorescence LT codes can be measured with the excitation and emission wavelength, thus reducing instrument costs. Moreover, LTs should not depend on emitter concentration. Unlike organic dyes, the LTs of which are typically < 10 ns, the fluorescence LTs of ternary semiconductor QDs that represent a “green” alternative to conventional Cd-containing QDs are in the range of several hundred ns, independent of oxygen concentration, and can be tuned to a certain extent by chemical composition and surface chemistry. This present a time region that can be barely covered by other emitters that have either much shorter or longer lifetimes. In this project, different encoding strategies will be assessed and the encoded particles will be then used for fluorescence assays for the analysis of several targets in parallel. Therefor the encoded particles will be functionalized with different target-specific bioligands and read out with a specifically designed flow cytometer enabling time-resolved fluorescence detection. With this instrument, the particles will be discriminated by their fluorescence LTs In one detection channel while the analytes will be quantified by fluorescence labels in a second channel in the intensity domain. T2 - Bad Honnef Physics School Exciting nanostructures: Characterizing advanced confined systems CY - Bad Honnef, Germany DA - 21.07.2019 KW - Multiplexing KW - Lifetime KW - Bead KW - Flow cytometry KW - Fluorescence KW - Quantum dot KW - InP KW - AIS KW - Dye KW - Encoding KW - Barcoding KW - Assay KW - Method PY - 2019 AN - OPUS4-49723 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 - Resch-Genger, Ute A1 - Weigert, Florian A1 - Frenzel, Florian A1 - Würth, Christian A1 - Hoffmann, Katrin A1 - Martynenko, Irena A1 - Dhamo, Lorena T1 - Photoluminescence Properties of Different Types of Nanocrystals at the Ensemble and Single Emitter Level N2 - Correlating the photoluminescence (PL) properties of nanomaterials like semiconductor nanocrystals (QDs) and upconversion nanocrystals (UCNPs) assessed in ensemble studies and at the single particle level is increasingly relevant for applications of these nanomaterials in the life sciences like bioimaging studies or their use as reporters in microfluidic assays. Here we present a comparison of the spectroscopic properties of ensembles and single emitters for QDs like II/VI QDs and cadmium-free AIS/ZnS QDs as well as different UCNPs. The overall goal of this study was to derive particle architectures well suited for spectroscopic and microscopic applications. T2 - BIOSSPIE CY - San Francisco, CA, USA DA - 02.02.2019 KW - Quantum yield KW - Nanomaterial KW - Photoluminescence KW - Absolute fluorometry KW - Integrating sphere spectroscopy, KW - NIR KW - IR KW - Fluorescence KW - Nanoparticle KW - Semiconductor KW - Quantum dot KW - Single particle spectroscopy KW - Surface chemistry PY - 2019 AN - OPUS4-47358 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Dhamo, Lorena A1 - Würth, Christian A1 - Raevskaya, A. E. A1 - Stroyuk, O. L. A1 - Gaponik, N. A1 - Eychmüller, A. A1 - Resch-Genger, Ute T1 - Syntheses and characterization of 2-4nm AgInS2/ZnS quantum dots N2 - Ternary semiconductors Quantum Dots (t-QDs) like AgInS (AIS) QDs are interesting alternatives to Cd-based QDs for applications as optical active materials in light-emitting diodes (LEDs), solar concentrators and solar cells as well as as biodiagnostic tools, respectively. AIS QDs exhibit broad photoluminescence (PL) spectra in the visible and near infrared, which are tunable by size and chemical composition (ratio of components or doping). In order to enhance the PL quantum yield (PL QY or Fpl) and prevent material deterioration and oxidation, these QDs are covered by ZnS shell. Here we show a spectroscopic study of differently colored AIS QDs synthesized in water, evaluating their PL properties, their PL QY and their PL decay. The simple aqueous synthesis that avoids further ligand exchange steps for bioanalytical applications, the tunable emission color, the high PL QY, the high absorption coefficients and the long lifetime make these t-QDs promising Cd-free materials as biodiagnostic tools or optical active materials. T2 - Summer School "EXCITING NANOSTRUCTURES" CY - Bad Honnef, Germany DA - 17.07.2017 KW - Semiconductor KW - Nanoparticle KW - Quantum dot KW - Flourescence KW - Synthesis KW - Spectral multiplexing KW - Ternary quantum dot PY - 2017 AN - OPUS4-41173 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Weigert, Florian A1 - Guhrenz, C. A1 - Strelow, C. A1 - Gaponik, N. A1 - Eychmüller, A. A1 - Mews, A. A1 - Resch-Genger, Ute T1 - Probing the bright and dark fraction of core-shell CdSe nanocrystals with single particle spectroscopy N2 - "The optical properties of semiconductor nanocrystals (SCNC) are controlled by constituent material, particle size, and surface chemistry, specifically the number of dangling bonds favoring nonradiative deactivation. This can lead to a distribution of photoluminescence Quantum yields (PL QY) amongst the SCNC particles, i.e., mixtures of “bright” and “grey” or “dark” SCNCs. Particularly the number of absorbing, yet not emitting particles can have a significant effect on the PL quantum yield obtained in ensemble measurements, leading to ist underestimation. The “dark fraction” is not assessable in common ensemble measurements; it can be probed only on a single particle level using a confocal laser scanning microscope coupled with an AFM. Such a setup was used to study core‐shell CdSe SCNCs with different shells and surface chemistries. Special emphasis was dedicated to correlate brightness, blinking, dark fraction, and decay kinetics of the single SCNCs with the ensemble PL QY and the PL decay kinetics. The results of this study can help to identify new synthetic routes and surface modifications to colloidally and photochemically stable SCNCs with a PL QY of close to unity." T2 - Summer School "EXCITING NANOSTRUCTURES" CY - Bad Honnef, Germany DA - 17.07.2017 KW - Semiconductor KW - Nanoparticle KW - Quantum dot KW - Flourescence KW - CdSe KW - Shell KW - Surface chemistry KW - Single particle spectroscopy PY - 2017 AN - OPUS4-41192 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Resch-Genger, Ute A1 - Würth, Christian A1 - Kaiser, Martin 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 -