Size dependent fluorescence and Raman characterization of nanoparticles by means of a novel analytical ultracentrifuge

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Particle properties depend on dispersity (particle size, shape, surface and inner structure) and composition. In order to fully exploit these property functions in technical applications, comprehensive multi-dimensional characterization methods are required. Developments in recent years in the field of analytical ultracentrifugation with integrated multi-wavelength absorption optics have already demonstrated the unmatched resolution, accuracy and reproducibility of size, shape, density and spectral absorption property characterization. Objective of this proposal is the development of in situ fluorescence and Raman spectroscopy within an analytical ultracentrifuge. The measurement of fluorescence spectra during sedimentation in an adjustable centrifugal field enables the simultaneous characterization of disperse properties including size, shape, density and, for the first time, also the emissive properties of nanoparticles. The separation of the particles during sedimentation gives access to even broad distributions and allows the determination of dispersity-dependent emission properties. The new method is applicable for quantum dots, plasmonic noble metal colloids, new 2D materials and proteins and their aggregates. Raman analysis gives access to size-dependent particle composition and structure (e.g. for carbon allotropes such as carbon nanodots, graphene or CNTs). Within this project, the new optical setup shall be integrated into a preparative ultracentrifuge and validated with reference materials. The next steps comprise the development of novel measurement methods and data acquisition software. Measurements for various cutting-edge particle systems shall demonstrate the new capabilities and will allow deeper understanding of the studied particle systems.