Regensburg 2016 – scientific programme
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 33: Ionic Liquids and Water
CPP 33.11: Talk
Wednesday, March 9, 2016, 12:30–12:45, H40
Analysis of the Electronic Structure of Aqueous Urea and its Derivatives: A combined Soft X-Ray - TD-DFT Approach — •Marc F. Tesch1, Ronny Golnak1,2, Felix Ehrhard1, Daniela Schön1,2, Jie Xiao1, Annika Bande1, and Emad F. Aziz1,2 — 1Helmholtz-Zentrum Berlin für Materialien und Energie, Berlin, Germany — 2Freie Universität Berlin, Germany
For a comprehensive understanding of biophysical and chemical processes a detailed knowledge about a molecules electronic structure is essential. A powerful method to achieve this is the use of synchrotron radiation, which allows to investigate a sample on an element selective level. Here soft X-ray spectroscopic measurements combined with time dependent density functional theory calculations are presented to investigate the electronic structure of urea and its derivatives acetamide, thiourea, dimethylurea, and biuret. The molecules were dissolved in water to include solvent effects on the molecular structure. The focus of this study lies on X-ray absorption, emission, and resonant inelastic scattering measurements at the nitrogen K-edge. By combining these techniques information about the occupied and unoccupied molecular states can be obtained. It will be shown that for a proper interpretation of the experimental spectra it is crucial to consider the localized nature of the X-ray interaction at the nitrogen sites of the molecules and a thorough comparison to calculated spectra is inevitable. This is demonstrated by discussing the chemical relevant HOMO-LUMO gap, a property which is directly accessible from the measurements.