Temperature induced mobility and recombination of atomic oxygen in crystalline Kr and Xe. I. Experiment

Abstract

Recombinant molecular spectra of O2 in crystalline Kr and Xe, obtained from sudden recombination induced by laser pumping of the predissociative B state, and by adiabatic recombination induced thermally, are reported. All electronic states that correlate with O(3P)+O(3P) are populated by both methods in Kr. The excited triplet states are strongly perturbed in Xe. Laser induced fluorescence (LIF) spectra of atomic O are also reported. Two emissions are observed in Kr; one at 563 nm with a radiative lifetime of 11 μs, and another at 599 nm with a radiative lifetime of 1.4 μs. These are assigned to emissions from neutral O(1S) trapped in substitutional and interstitial octahedral sites, respectively. O atoms are generated in situ by photodissociation of either O2 or N2O. The subsequent thermally induced recombination of atoms is followed using LIF from atomic centers and molecular thermoluminescence. The recombination follows first order kinetics, from which it is inferred that atomic mobilities are characterized by long-range migration, with migration lengths of ≥300 Å. Site specific Arrhenius rate constants are extracted from the analysis of glow curves. Only two sites, interstitial and substitutional Oh, contribute to the glow curves in crystalline Kr. A third site is present in crystalline Xe. A broad distribution of activation energies is observed in vapor deposited matrices.