Reactive quenching of two-photon excited xenon atoms by Cl2

Abstract

Total binary and tertiary quench rates have been measured for the reaction Xe (5p5np, np′, n=6,7)+Cl2 at thermal temperatures. Xenon atoms are excited by state-selective, two-photon absorption with an ultraviolet laser. The time-dependent fluorescence from the excited atom in the infrared, visible, and from XeCl* (B) product near 308 nm have been measured with subnanosecond time resolution. The decay rates are measured as a function of Cl2 pressure to 20 Torr and Xe pressure to 400 Torr. The measured reaction rates (k2∼10−9 cm3 s−1) are consistent with a harpoon model described in a separate paper. We also measure large termolecular reaction rates for collisions with xenon atoms (k3∼10−28 cm6 s−1). Total product fluorescence has been examined using a gated optical multichannel analyzer. We measure unit branching fractions for high vibrational levels of XeCl* (B) with very little C state fluorescence observed.