Cars observation of fine structure population inversion from atomic quenching: S( 1D)+Ar→S( 3P 0)+Ar

Abstract

In this first use of CARS spectroscopy to detect atomic sulfur, a population inversion has been observed among the fine structure levels of ground term S( 3P J ) produced in the quenching of S( 1D) by collision with argon. At least 80% of the S( 3P J ) is formed in the J=0 level. ArS potential curves obtained from MC SCF CI calculations provide the basis for a proposed mechanism explaining this high level of quenching selectivity.