Experimental and theoretical study of the collisional quenching of S(1D) by Ar

Abstract : We present an experimental and theoretical investigation of the deactivation rate of S(1D) atoms by collisions with argon. Kinetic measurements were performed at temperatures from 5.8 K to 298 K in cold uniform supersonic flows using a CRESU (Cinétique de Réaction en Ecoulement Supersonique Uniforme or Reaction Kinetics in a Uniform Supersonic Flow) apparatus. In order to simulate them, ab initio electronic structure calculations using internally contracted MRCI methodology were performed to describe the interaction. Starting from them, close-coupling calculations were carried out to determine collisional quenching probabilities for the transition S(1D) → S(3P) in the energy range 1-3000 K (1 K ≈ 0.7 cm-1), sufficient to calculate thermal rate coefficients up to 300 K. Stückelberg-like oscillations in the quenching probabilities as a function of the energy are found and interpreted using a semiclassical model. Differences between the temperature dependence of the experimental and theoretical rate coefficients are detected at low temperatures. They are discussed in the light of a study of the high sensitivity of the theoretical results to the potential curves, due to the interference mechanisms which underlie the process. © 2017 the Owner Societies.
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M. Lara, C. Berteloite, M. Paniagua, F. Dayou, Sébastien D. Le Picard, et al.. Experimental and theoretical study of the collisional quenching of S(1D) by Ar. Physical Chemistry Chemical Physics, Royal Society of Chemistry, 2017, 19 (42), pp.28555-28571. ⟨10.1039/c7cp05279k⟩. ⟨hal-01638857⟩



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