Structural and spectroscopic effects of vibronic coupling in the C 2F radical

Abstract

The lowest three (1 2A ′,2 2A ′,1 2A ′′) potential energy surfaces of the C 2F radical have been studied at the ab initio level, using Multi Reference Configuration Interaction techniques. For linear geometries, the three surfaces correlate with a 2 Π and a 2 Σ + state, which are very close in energy. Only the X 2A ′ ground state was found to be bent, with R CC=1.271 Å; R CF=1.276 Å; ∠CCF=165°, and a barrier to linearity of 275 cm −1. The spin–rovibronic energy levels up to J=7/2 have been calculated using a recently developed method [Carter et al., Mol. Phys. 98 (2000) 1967]. Almost all of the resulting levels arise from a strong mixture of two out of three electronic states and their assignment is intrinsically ambiguous. A partial characterization, based on the shape of the vibronic wavefunctions, has been made.