Electronic and vibrational relaxation of CO in Ar and Kr matrices

Abstract

Vibrational progressions due to radiative decay of e 3Σ(ν′ = 0, 4, 6, 8), a′ 3Σ(ν′2,6), d 3Δ(ν′= 4, 6, 8) and a 3Π(ν′=0) to the ground state or to the a 3Π state have been observed for CO in Ar and of e 3Σ(ν′ = 4, 8) and d 3Δ(ν′ = 4, 8) for CO in Kr by selective excitation of A 1Π(ν′ = 0, … 8). The bottlenecks, the intersystem crossing and the internal conversion rate constants are explained by an intramolecular mixing of electronic states and electron-phonon coupling with the matrix. For internal conversion in the singlet states an additional matrix-induced nonadiabatic matrix element exceeding 20 cm −1 has to be postulated for Kr. A long-lived Rydberg state is observed for CO/Ar.