Collision-induced electronic energy transfer from v=0 of the E(0g+) ion-pair state in I2: Collisions with He and Ar

Abstract

The electronic energy transfer pathways that occur following collisions between I 2 in the E ion-pair electronic state ͑vϭ0, Jϭ55͒ and He and Ar atoms have been determined. The nearby D, DЈ, and ␤ ion-pair states are populated, but with relative branching ratios that vary with the rare gas collision partner. In He/I 2 collisions, the D state is preferentially populated, while Ar/I 2 collisions preferentially populate the ␤ electronic state. Bimolecular rate constants and effective hard sphere collision cross sections have been determined for each channel; the cross sections range from 7.0Ϯ1.0 Å 2 for populating the ␤ state with Ar collisions to 0.9Ϯ0.2 Å 2 for populating the DЈ state with He collisions. For both rare gas collision partners, and all three final electronic states, low vibrational levels are populated, in rough accord with the relevant Franck-Condon factors. There is little propensity observed for population of vibrational levels that are in near resonance with the initially prepared level in the E state.

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][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.…”

The influence of amplified spontaneous emission in collisional energy transfer studies exemplified by to transfer in I2

“…D0 þ u ð 3 P 2 Þ transfer is mainly by collisions rather than by ASE. Fecko et al [17] carried out a detailed study of the collisional transfer from E0 þ g ð 3 P 2 Þ (v = 0) using He, under non-ASE conditions, and showed that (v = 0-3) of the D0 þ u ð 3 P 2 Þ state were populated to a similar degree.…”

“…X0 þ g (aa) emission is observed. Although Fecko et al [17] did not use Xe as a collision partner, they did observe an increase in the efficiency of the E0 þ g ð 3 P 2 Þ ! D 0 2 g ð 3 P 2 Þ/b1 g ( 3 P 2 ) transfer relative to the E0 þ g ð 3 P 2 Þ !…”