I AND I* FORMATION MECHANISM FORMED BY CH3I CLUSTERS AT 280 NM PHOTODISSOCIATION T. Murase, D.-C. Che, M. Hashinokuchi, and T. Kasai Department of Chemistry, Graduate School of Science,Osaka University, Toyonaka Osaka 560-0043, Japan Photodissociation dynamics of CH3I clusters at 280 nm was investigated by REMPI-TOF measurement. TOF spectra of the directly formed I atoms from photodissociation of the clusters were observed. It was found that the translational energy for I formation is substantially relaxed compared with that for I* formation, and that the branching ratio of I / I* is increased in cluster photodissociation relative to monomer. Results were discussed in terms of cage effect in cluster.