Resonant multiphoton ionization spectrum and electronic structure of CH radical. New states and assignments above 50 000 cm−1

Abstract

Resonant multiphoton ionization spectra, with mass and photoelectron analysis, of photolytically produced CH radical yields previously unobserved bands arising from two-photon transitions to Rydberg and highly excited valence states. Rotational analysis of the spectrum for m/e=13, coupled with vibrational labeling of the resonant state by photoelectron kinetic energy analysis, identifies a new state, designated E′ 2Σ+. Breaking off of rotational structure near N′=11 in the v=2 level of the D 2Πi state is attributed to predissociation by a doubly excited potential curve calculated to lie in this energy region. Comparison is made with earlier absorption spectra taken following flash photolysis.