Dynamics and mechanism of the non-adiabatic transitions from the ungerade I2(D0+u) state induced by collisions with rare gas atoms

M. E. Akopyan, E. I. Khadikova, S. S. Lukashov, S. A. Poretsky, A. M. Pravilov, A. A. Buchachenko, Yu V. Suleimanov

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7 Citations (Scopus)

Abstract

The stepwise three-photon two-color laser excitation scheme is used for selective population of the first-tier ion-pair D0+u state of molecular iodine. Collection and analysis of the luminescence after the excitation of the vD = 6, 8, 13 and 18 vibronic levels of the D state in the pure iodine vapor and the gas-phase mixtures with He, Ar and Xe provide the total and, whenever possible, partial rate constants for the collision-induced non-adiabatic transitions to the other ion-pair states of the first tier. Comparison with the analogous data obtained previously for the non-adiabatic transitions from the E0+g state reveals the similarity between two cases. For He, the D ↔ E transitions are preferable, whereas for Ar and Xe transitions to the D′ and β states dominate at vD = 6, 8 and 13, in accord with the statistical considerations. Efficient population of the δ state at vD = 18 in Ar and Xe is the most prominent non-statistical feature observed. The vibrational product state distributions for the D → E transitions are also obtained. In contrast to the previously studied E → D transition, they show significant positive vibronic energy transfer. The measurements for He and Ar are accompanied by the quantum scattering calculations that reproduce well the main qualitative features of the experimental results.

Original languageEnglish
Article number244304
JournalJournal of Chemical Physics
Volume133
Issue number24
DOIs
Publication statusPublished - 28 Dec 2010
Externally publishedYes

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