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MO: Fachverband Molekülphysik
MO 32: Poster: Experimental Techniques
MO 32.5: Poster
Thursday, March 17, 2011, 16:00–18:00, P1
Soft x-ray absorption spectroscopy of ultrathin liquid films — •Simon Schreck, Christian Weniger, Gianina Gavrilla, and Philippe Wernet — Institute for Methods and Instrumentation for Synchrotron Radiation Research, Helmholtz-Zentrum Berlin
Applying soft x-rays to liquid samples is a challenging task due to the incompatibility of the vacuum environment required for soft x-rays and the high vapor pressure of liquids. When recording soft x-ray absorption spectra in transmission mode, which is the most direct and efficient way, the strong attenuation of soft x-rays in nearly all elements calls for ultrathin samples. For water and aqueous solutions, sample thicknesses clearly below one micrometer are necessary.
Here we present an experimental setup for preparing ultrathin liquid films separated from vacuum or He atmosphere with controllable thickness from nm to µm. These ultrathin liquid films allow for transmission measurements with soft x-rays to record high quality soft x-ray absorption spectra of different kinds of samples such as bulk liquid water (H2O) and heavy water (D2O), aqueous salt solutions and solvates molecules. The high quality and reproducibility of the spectra is shown by comparing measured data with reference data and the high sensitivity for small structural differences is demonstrated by resolving the spectral differences in the x-ray absorption spectra of H2O and D2O. Furthermore the data prove the ability to measure solvated systems and solutions at very low concentrations of down to the millimol/l range. The measurements were performed at the synchrotron radiation source BESSYII at the Helmholtz-Zentrum Berlin.