Back to Search Start Over

Dynamics and mechanism of the E→D, D′, β, γ, and δ nonadiabatic transitions induced in molecular iodine by collisions with CF4 and SF6 molecules.

Authors :
Akopyan, Mikhail E.
Lukashov, Sergey S.
Poretsky, Sergey A.
Pravilov, Anatoly M.
Torgashkova, Anna S.
Buchachenko, Alexei A.
Suleimanov, Yury V.
Source :
Journal of Chemical Physics; 9/21/2008, Vol. 129 Issue 11, p114309, 9p, 1 Diagram, 2 Charts, 4 Graphs
Publication Year :
2008

Abstract

Nonadiabatic transitions among the first-tier ion-pair states of the iodine molecule in collisions with CF<subscript>4</subscript> and SF<subscript>6</subscript> partners are investigated by detecting the luminescence following the optical-optical double resonance excitation of the E0<subscript>g</subscript><superscript>+</superscript>-state to the vibrational levels v<subscript>E</subscript>=8, 13, and 19. Total and partial rate constants, as well as vibrational product state distributions, are determined. It is found that electronic energy transfer in all channels is predominantly assisted by excitation of the dipole-allowed ν<subscript>3</subscript> and ν<subscript>4</subscript> modes of the partner. The measurements are accompanied by quantum scattering calculations that implement a close coupling treatment for the electronic and vibrational degrees of freedom and combine diatomics-in-molecule and long-range models for diabatic potential energy surfaces and coupling matrix elements. The analysis of experimental and theoretical data shows that the transitions without excitation of the partner are due to short-range couplings, whereas the vibrational excitation of the partner in the D0<subscript>u</subscript><superscript>+</superscript> channel originates from the long-range coupling of two transition dipole moments: electronic of the iodine molecule and vibrational of the partner. Unexpectedly efficient excitations of the partner in the other ion-pair states, which are not coupled to the initial E0<subscript>g</subscript><superscript>+</superscript>-state by the transition dipole, are interpreted within the postcollision mechanism. Qualitatively, this implies that during a single collision the long-range nonadiabatic transitions to D, ν<subscript>3</subscript> and D, ν<subscript>4</subscript> channels are followed by secondary short-range transitions without changing the state of the partner. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
00219606
Volume :
129
Issue :
11
Database :
Complementary Index
Journal :
Journal of Chemical Physics
Publication Type :
Academic Journal
Accession number :
34481205
Full Text :
https://doi.org/10.1063/1.2978170