Theoretical and experimental studies of a new predissociation in theA2Δ state of CCl

Abstract

The A ²Δ-X ²Π transition of CCl has been studied with the High Frequency Deflection (HFD) technique. Lifetimes were measured for the ν′ = 0, 1 and 2 vibrational levels of the A ²Δ state. A drastic shortening of the lifetime going from ν′ = 0 to ν′ = 1 indicated that a predissociation takes place. In order to obtain more information about this predissociation, potential energy curves were calculated with the CASSCF method and the contracted CI method for the bound X ²Π and A ²Δ states and several repulsive states. It was found that the dominating cause of the predissociation is a ²Π state going to the ground state dissociation products. Electronic matrix elements were roughly estimated and the bound-continuum vibrational overlap integrals were calculated. The A ²Δ-²Π crossing point was adjusted until satisfactory agreement was obtained between experimental and theoretical predissociation rates for ν′ = 1.