Iodine effect on the relaxation pathway of photoexcited I−(H2O)n clusters

The iodine effect on the photoexcited I−(H2O)n relaxation pathway is studied using ab initio calculations. Critical behavior of the vertical binding energy (VBE) of the excited I−(H2O)n is seen at short distances between the iodine and the remaining (H2O)n, which is correlated to the rapid experimental VBE increase within 1 ps (L. Lehr, M.T. Zanni, C. Frischkorn, R. Weinkauf, D.M. Neumark, Science 284 (1999) 635). Further comparisons of computed results with experimental data reveal that iodine detachment is a crucial step in the cluster relaxation dynamics, intrinsically different from the electron-detachment pathway of photoexcited aqueous iodide.