Spectroscopy and relaxation dynamics of I2Arn clusters. Geminate recombination and cluster fragmentation

Abstract

I2Arn clusters yield visible and near-UV emissions when excited to the states which correlate with the first ion-pair manifold of I2. These states may be accessed by 193 nm excitation of ground-state clusters, or near-UV excitation of electronically metastable I 2(A′ or A)Arm. Comparisons of the cluster and I 2/Ar matrix spectra suggest that such excitations result in fragmentation and "melting" of the clusters prior to emission. 532 nm photodissociation of I2 within the clusters is followed by geminate recombination which populates the A′, A, and X states. The probability for ejection of the recombined I2 from the clusters during the relaxation process appears to be size dependent. These results represent tentative steps towards the study of I(2P3/2)+ I( 2P3/2) recombination in Ar clusters. They also indicate that dissociation, recombination, and fragmentation processes may be used as a general method for generating metastable species in supersonic expansions. © 1992 American Institute of Physics.