Photo- and autoionization processes of superexcited iodine atoms in MPI of CH3I and HI

Abstract

REMPI data was recorded for CH3I and HI for the two-photon excitation region of 76,680–82,620 cm−1. I+ signals reveal number of peaks of varying line widths and intensities. These are attributed to two-photon resonant excitation of iodine atoms I(2P3/2) and I*(2P1/2) to Rydberg and superexcited states followed by one-photon ionization and autoionization. Laser power dependence experiments and line intensities reveal that the photoionization of I/I* follows one-photon molecular dissociation. Quantum defect analysis and correlation inspections of line widths were applied to identify and characterize number of new, not previously observed, superexcited atomic states of ion cores 3P0,1 and 1D2. Mechanisms of autoionization processes are summarized and discussed. Particularly fast autoionization processes of superexcited iodine atoms of ion core 1D2 are observed. Comparison of observed line widths with expected trends in n proved to be very useful in the analysis procedure and to identify state interactions.