Dresden 2009 – scientific programme
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 39: POSTERS Colloids and Liquids
CPP 39.29: Poster
Thursday, March 26, 2009, 17:00–19:30, P3
Tetrahydrofuran clathrate hydrate formation studied by x-ray Raman scattering — •Heiko Conrad1, Felix Lehmkühler1, Christian Sternemann1, Arto Sakko2, Omid Feroughi1, Laura Simonelli3, Simo Huotari3, Dietmar Paschek4, Keijo Hämäläinen2, and Metin Tolan1 — 1TU Dortmund, Fak. Physik/DELTA, Dortmund, Germany — 2Div. Mat. Phy., Dep. of Physics, U Helsinki, Finland — 3ESRF, Grenoble, France — 4Rensselaer Polytechnic Institute, Troy, NY, USA
The formation of clathrate hydrates in the system water-Tetrahydrofuran (THF) was studied by means of non-resonant x-ray Raman scattering (XRS). Hydrates are ice-like inclusion compounds where guest molecules are embedded in water nano-cages. A possible future application of hydrates is the storage of gases, in particular H2 in THF hydrate for fuel cells. Therefore, a detailed knowledge of the hydrate formation process is important.
XRS is an energy loss spectroscopy which allows to measure light element x-ray absorption using hard x-rays. In the dipole limit XRS directly corresponds to x-ray absorption spectroscopy (XAS). XRS spectra are sensitive to possible hydrate precursors in a supercooled state and thus yield unique information about the hydrate formation process. X-ray Raman spectra of the oxygen K-edge were measured of the hydrate, of a supercooled liquid THF/water mixture, and of a mixture at a temperature above the region of hydrate stability. The measurements were compared with DFT calculations employing local structures obtained from molecular dynamics simulation snapshots.