Experimental and theoretical studies of CO vibrational relaxation by He atoms

Abstract

Rate constants for the vibrational relaxation of 12C16O(v=1) and 13C18O(v=1) by 4He and 3He over an ab initio potential surface have been calculated with a vibrational close-coupling, rotational infinite order sudden (VCC-IOS) technique. Improved experimental measurements of the relaxation of 12C16O(v=1) by 4He and new measurements of the deactivation of 13C18O(v=1) by 4He and 3He all over the temperature range 300–80 K have been carried out with a laser fluorescence method. These rate constants and existing ones for the deactivation of 12C16O by 4He over the temperature range 2300–580 K and by 3He over the temperature range 300–80 K are compared with the theoretical rate constants. The rate constants vary by over six orders of magnitude but the calculations reproduce the experimental values well. These results give evidence for the accuracy of the potential energy surface and the (IOS) technique.