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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 2: Focus: Soft Matter and Nanocomposites - New opportunities with advanced neutron sources I
CPP 2.2: Vortrag
Montag, 16. März 2020, 10:00–10:15, ZEU 222
Reducing the recording time of neutron spectroscopy measurements to investigate kinetic processes — •Christian Beck1,2, Marco Grimaldo1, Felix Roosen-Runge3, Olga Matsarskaia1, Frank Schreiber2, and Tilo Seydel1 — 1Institut Laue Langevin, Grenoble, France — 2University of Tübingen, Germany — 3Malmö University, Malmö, Sweden
Recent developments at the neutron backscattering spectrometer IN16b (ILL, Grenoble) allow to collect high energy resolution (δ E≈ 0.9µeV) measurements at constant non-zero energy transfers, also called fixed window scans (FWS). Full quasi-elastic neutron scattering (QENS) spectra need to be measured for several hours while FWS only need measurement times of several minutes. Different models are established for the analysis of elastic FWS. The approaches for inelastic FWS are limited. The shorter measurement time allows to follow the short-time self-diffusive processes of kinetically changing samples. Here, slowly crystallizing protein solutions were used as a model system. We present different frameworks to analyze these data, extracting generalized mean-squared displacements [1] and global diffusion coefficients and to separate the different hierarchical contributions. The results are compared with analyzed floating average full QENS spectra with a time resolution of 15 min [2]. In addition, time-dependent neutron spin echo measurements, collected on the same systems, offer access to the short-time collective dynamics of the sample. [1] F. Roosen-Runge et al.; EPJ Web of Conf. 83, 02015 (2015) [2] C. Beck et al.; Cryst. Growth Des.; DOI:10.1021/acs.cgd.9b00858