Oxygen K-edge X-ray absorption near edge structures (XANES) of sublimated films of amino acids

Tanaka, Masahito*; Nakagawa, Kazumichi*; Koketsu, Toshiyuki*; Agui, Akane; Yokoya, Akinari

Journal of Synchrotron Radiation, 8(Part2), p.1009 - 1011, 2001/03

Amino acid molecules are known to be in the state of so-called "zwitter-ion" in solid phase and its extremely low vapour pressure makes ultra high vacuum experiment such as the XANES experiment possible. Recently, C-K edge XANES spectra of aromatic amino acids were studied experimentally and theoretically. Here we selected oxygen K-edge for XANES study of amino acids. From the view point of K-edge XANES study in amino acids, oxygen is interesting because its chemical states have the wealth of variety. A carboxylic group on the carbon is in the state of carboxylic anion -COO-, while carboxylic group in side-chain stays on -COOH, and some amino acids have -OH group in side-chain. Due to this variety of chemical environment, we can expect characteristic chemical shift for each oxygen atom in various amino acids. In this paper, we report a result of oxygen K-edge XANES spectra of amino acids (glycine, L-a-alanine, b-alanine, L-serine, L-asparic acid and L-tyrosine) films. We discuss the details of spectra on the basis of DV-X calculation.