XAFS analysis of triiodide ion in solutions

Iodine K-edge XAFS of triiodide ions in various solvents were measured at SPring-8 BL01B1 and analyzed. Though the anion takes a linear and symmetric form, the second peak expected from enhanced multiple scatterings can be hardly observed because of its large vibrations. The bond distances and the Debye-Waller factors for the I-I couple vary when protic solvents were used. It was indicated that the larger the Mayers' acceptor number of the solvent is, the larger the Debye-Waller factor is. It was also found that among the aprotic solvents, the larger the Gutmann's donor number is, the smaller the Debye-Waller factor is.