Ab initio investigation of the vibronic structure of the C<inf>2</inf>H spectrum: Computation of the vibronically averaged values for the hyperfine coupling constants

Abstract

The vibronically averaged values for the hyperfine coupling constants in the X2Σ-A2Π system of the ethynyl radical are computed by means of the ab initio method calculations. The results point at the importance of taking into account the coupling of all three electronic states in question (12A′, 22A′, and 12A″) for a reliable explanation of the available experimental findings. The mean values of the hfcc's for K = 0 and 1 levels in 13C2H and 13C2D in the energy range up to 6000 cm-1 are predicted. © 1991.