XAFS analysis of triiodide ion in solutions

Iodine K-edge XAFS of triiodide ions in various solvents were measured at S Pring-8 BL01B1 and analyzed. Though the anion takes a linear and symmetric form, the second peak expected from enhanced multiple scatterings can be ha rdly observed because of its large vibrations. The bond distances and the D ebye-Waller factors for the I-I couple vary when protic solvents were used and they were similar when aprotic solvents were used. It was indicated tha t 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 fact or is.