Rovibrational resonance effects in collision-induced electronic energy transfer: I_2(E,v=0-2) + CF_4

摘要

Collisions of I_2 in the E(0_g~+) electronic state with CF_4 molecules induce electronic energy transfer to the nearby D,beta,and D' ion-pair states.Simulations of dispersed fluorescence spectra reveal collision-induced electronic energy transfer rate constants and final vibrational state distributions within each final electronic state.In comparison with earlier reports on I_2(v_E=0-2) collisions with He or Ar atoms,we find markedly different dynamics when I_2,excited to the same rovibronic states,collides with CF_4.Final vibrational state distributions agree with the associated Franck-Condon factors with the initially prepared state to a greater degree than those found,with He or Ar collision partners and suggest that internal degrees of freedom in the CF_4 molecule represent a substantial means for accepting the accompanying loss of I_2 vibronic energy.Comparison of the E->D transfer of I_2 excited to the J=23 and J=55 levels of the v_E=0 state reveals the onset of specific,nonstatistical dynamics as the available energy is increased above the threshold for excitation of the low frequency v_2 bending mode of CF_4.