Non-adiabatic E→MD, D′, β, γ, δ transitions in the first ion-pair tier of molecular iodine induced by collisions with I2, N2 and CO2

Optical-optical double resonance spectroscopy is used to obtain total rate constants, electronic branching ratios, and vibrational product state distributions for non-adiabatic transitions among the first-tier ion-pair states of the I2 molecule excited to the E0g+, vE = 8, 13, 19; JE ≈ 55 rovibronic levels in collisions with M = I2, N2 and CO2. It is shown that I2(E→MD) near-resonant transitions are caused by the interaction between the transition dipole moment of I2(E-D) and the electric quadrupole moment of M. Besides, there are transitions induced by polarization interactions of the collision partners. Wide non-resonant vibrational distributions at the final states correspond to them. The I2(D and β) state vibrational levels populated in the transitions accompanied by excitation of IR active vibrational mode, CO2(0110 ← 000) ν2e1u(667 cm−1), are observed. It is shown that rotational excitation of the collision partners can compensate energy mismatch between initial and final rovibrational levels.