Franck-Condon effects in collision-induced electronic energy transfer: I2(E;v=1,2)+He, Ar

Abstract

Collisions of I2 in the E electronic state with rare gas atoms result in electronic energy transfer to the D, beta, and D' ion-pair electronic states. Rate constants for each of these channels have been measured when I2 is initially prepared in the J = 55, nu = 1 and 2 levels in the E state. The rate constants and effective hard sphere collision cross sections confirm the trends observed when nu = 0 in the E state is initially prepared: He collisions favor population of the D state, while Ar collisions favor population of the beta state. Final state vibrational level distributions are determined by spectral simulation and are found to be qualitatively consistent with the trends in the Franck-Condon factors. The experimental distributions are also compared to the recent quantum scattering calculations of Tscherbul and Buchachenko.

Theoretical and experimental studies of collision-induced electronic energy transfer from v=–3 of the E(g+) ion-pair state of Br2: Collisions with He and Ar

“…4 has an additional contribution from a bimodal series of peaks with maxima near 262.2 and 274.5 nm, indicative of emission from v D = 1. 10,12 Whereas He and Ar collisions produced similar vibrational state distributions in the IP pair states of iodine, our present results show markedly different dynamics between collisions of the Rgs with bromine. Our spectral fits allow for the emission from v D =0-4 and the small, additional peaks in the bottom half of Fig.…”

“…10,12,17,18 It is worthwhile to stress once again that the diabatic PESs and couplings for these systems are very similar; so differences in the dynamics should be expected to arise from the peculiarities of the IP state energy level structure. Comparison with similar processes in the I 2 ͑E͒ molecule previously studied by using the same methods allows further analysis of their relative importance.…”

“…10,12 However, the E → D transitions create sharply different vibrational distributions in the two molecules. 5, 7, and 8, for each of the final IP states ͑D , DЈ , ␤͒, the distributions of Franck-Condon factors with the E state possess sharp maxima.…”

“…[10][11][12][13] Double resonance excitation prepares bromine molecules in a single vibrational level of the E electronic state. [10][11][12][13] Double resonance excitation prepares bromine molecules in a single vibrational level of the E electronic state.…”

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] These studies have focused on the dynamics that accompany the collisions of I 2 following excitation to the E͑0 g + ͒ ion-pair ͑IP͒ state and document an important model system for examining nonadiabatic processes in molecules with dense rovibronic energy levels. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] These studies have focused on the dynamics that accompany the collisions of I 2 following excitation to the E͑0 g + ͒ ion-pair ͑IP͒ state and document an important model system for examining nonadiabatic processes in molecules with dense rovibronic energy levels.…”