Photodissociative production of O(1<i>S</i>) from N2O and S(1<i>S</i>) from OCS in rare gas matrices

Abstract

Photoluminescence excitation spectra of Ar:N2O (1%), Ar:OCS (1%), and Kr:OCS (1%) were obtained in the region 180–104 nm, using UV synchrotron radiation at SSRL. Photodissociation energy thresholds in the matrix were found to be: 8.06 eV for N2O→N2(X 1Σ+)+0(1S) and 7.17 eV for OCS→CO (X 1Σ+)+S(1S). Our results show several effects due to interactions between the matrix and the triatomic molecule: (1) differential blue shifts of the 1Π←1Σ+ and 1Σ+←1Σ+ transitions, (2) a greatly enhanced predissociation rate from 1Π to 1Σ+, (3) matrix dependent energy shifts of a particular Rydberg state, (4) nonradiative energy transfer between the matrix and the triatomic, involving either self-trapped excitons and a Foster–Dexter mechanism or free excitons and a harpooning mechanism. To our knowledge, this is the first observation of the free exciton–harpooning mechanism in a rare gas matrix.