Yasumasa HIKOSAKA (Tokyo Inst. Tech. and IMS), Hideo HATTORI, Takumi HIKIDA (Tokyo Inst. Tech.) and Koichiro MITSUKE
[J. Chem. Phys. 107, 2950 (1997)]
Neutral dissociation of superexcited states of OCS has been studied by two-dimensional photoelectron spectroscopy using synchrotron radiation in the photon energy range of 14.2 - 16.8 eV. A two-dimensional spectrum exhibits noticeable features which are assigned as resulting from autoionizing transitions of excited atomic sulfur S* from Rydberg states converging to S+(2Do) to S+(4So). The precursor molecular states leading to S* + CO are considered to be multiple-electron-excited Rydberg states, OCS*(Dis), converging to OCS+ with 2(SIGMA)- and/or 2(DELTA) symmetry. The electron signal counts due to autoionization of S* show enhancement at excitation photon energies for the Rydberg states OCS*(RB) converging to OCS+(B2(SIGMA)+). These results support a predissociation mechanism for the formation of S*: conversion from OCS*(RB) to OCS*(Dis).