193 nm photodynamics of NO in rare gas matrices: Fluorescence, thermoluminescence, and photodissociation

Abstract

193 nm excited time gated emission spectra of a NO monomer isolated in Ar, Kr, and Xe matrices are presented. In the Ar matrix a 4Π→X 2Π, B 2Π→X 2Π, and A 2Σ→X 2Π band systems are completely separable. In solid Kr, both B 2Π→X 2Π and A 2Σ→X 2Π appear promptly from the laser pulse, and in the Xe matrix only Rydberg A 2Σ→X 2Π fluorescence is observed. Prolonged photolysis at 193 nm yields electron paramagnetic resonance signals attributed to isolated S4 nitrogen atoms. This is the first observation of condensed phase photodissociation of NO. Annealing of the extensively irradiated Ar matrix produces strong a 4Π→X 2Π and B 2Π→X 2Π thermoluminescence emissions due to N(4S)+O(3P) recombination. In the Kr matrix thermoluminescence is entirely due to a 4Π→X 2Π transition. No thermoluminescence is observed in Xe. Thermoluminescence is ascribed to short-range trapping of N and O fragments, and well separated atoms do not have significant contribution to recombination.