Collisional deexcitation of metastable ions: A new technique to separate radiative and nonradiative contributions AIP Conf.Radiative lifetimes and bimolecular rates have been determined for two-photon laser excited states ofXe* (5p 5 6p, 5p 5 6p', 5p 5 7p) in argon and xenon buffer gases. The collisional deactivation rates are found to be very large for the Xe 6p' and 7p states [-(2-5) X lO-1O cm3/s] while the rates for the Xe 6p states are comparatively smaller [-(0.06-1.2) X lO-1O cm 3 /s]. In general, the quenching rates in argon are about a factor of 2 smaller than the xenon quenching rates for the same excited state with the notable exception ofXe 6p[ 112]0' For Xe 6p [ 112] 0' a multicomponent decay has been observed in argon buffer gases. The second component is attributed to collisional coupling to Xe 5d[ 112] 1 which lies 132.3 cm -I below Xe 6p [ 112] 0' Quench rates determined from the collisionally induced VUV fluorescence from Xe 5d[ 112] 1 at 125 nm are in excellent agreement with this assignment. Furthermore, these experiments have unambiguously identified the product channel involved in the curve crossings observed in studies of optical collisions [N.

Lifetimes and bimolecular quenching rate constants have been determined for two-photon laser excited states of Xe*(5p56p,5p56p′,5p57p) and Kr*(4p55p) in krypton and xenon buffer gases. Collisional mixing between Kr*5p[5/2]2 and Kr*5p[5/2]3 in krypton is observed and analyzed using a coupled two-state model to obtain the rate of mixing. The measured rate constants for quenching of Xe*(6p′,7p) by krypton are 15%–20% smaller than those measured previously in xenon while bimolecular rates for the Kr*(5p) states are an order of magnitude larger in xenon than those in a krypton buffer. Measurements of state-to-state rate constants for deactivation and excitation transfer are also reported for these states in krypton and xenon buffer gases.

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Total binary and tertiary quench rates have been measured for the reaction Xe (5p 5 6p)+ CI2 at thermal temperatures. Xenon atoms are excited by state-selective, twophoton absorption with a u.v. laser. The time dependent fluorescence from the excited atom in the I.R. and from XeCl* (B) product near 308 nm have been measured with subnanosecond time resolution.The decay rates are measured as a function of CI2 pressure to 20 Torr and Xe pressure to 400 Torr. The measured reaction rates (k2~10" 9 cm^sec^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" 2ĉ rrAec" 1). Total product fluorescence has been examined using a gated optical multichannel analyser. We measure unit branching fractions for high vibrational levels of XeCl* (B) with very little C state fluorescence observed. The measured termolecular rates suggest similar processes will dominate at the high buffer-gas pressures used in XeCl lasers. The effect of these large reactive cross sections for neutral xenon atoms on models of the XeCl laser will be discussed. DISCLAIMER This report was prepared as an account of work sponsored by an agency of the United States 1 S M f § >*F» Government. Neither the United States Government nor any agency thereof, nor any of their ffl, ^ , j \ fi employees, makes any wa.ranty, express or implied, or assumes any lepal liability or responsi-'rig liyf jj I bility for :hc accuracy, completeness, or usefulness of any information, apparatus, product, or process disclose.!, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof

Reactive quenching studies of Xe (6s,3 P 2) metastable atoms by chlorine containing molecules