Optical population of iodine molecule ion-pair states via MI2 vdW complexes, M = I2, Xe, of valence states correlating with the third, I(2 P 1/2) + I(2 P 1/2), dissociation limit

Abstract

The first results of measurements and analysis of excitation spectra of the λlum = 3250 A luminescence corresponding to I2(D0u+ → X0g+) transition as well as luminescence at λlum = 3400 A, where I2(D′2g → A′2u and/or β1g → A1u) transitions occur, observed after three-step, λ1 + λf + λ1, λ1 = 5321–5508.2 A, λf = 10644.0 A, laser excitation of pure iodine vapour and I2 + Xe mixtures at room temperature via MI2 vdW complexes, M = I2, Xe, of the I2(0g+, 1u(bb)) valence states correlating with the third, I(2P1/2) + I(2P1/2) (I2(bb)), dissociation limit are presented. Luminescence spectra in the λlum = 2200–3500 A spectral range are also analyzed. Strong luminescence from the I2(D) and, probably, I2(D′ and β) states is observed. We discuss three alternative mechanisms of optical population of the IP state. In our opinion, the mechanism including the MI2 complexes is the most probable.