Angle-velocity-resolved measurements of I(2P3/2,1/2) from (CH3I)n cluster photodissociation at 266 and 304 nm

The angle-velocity distribution of I(2P3/2) and I(2P1/2) from photodissociation of (CH3I)n clusters was measured at 266 and 304 nm. For the monomer (n = 1), the angular distribution is very anisotropic and the translational energy spectrum is sharply peaked at high energy. For clusters (predominantly n = 2, 3), the I atom undergoes collisions, which sunstantially relax the translational energy and anistropy. Three observations are reported. (1) A residual anisotropy exists in cluster photodissociation that increases with increasing fragment translational energy. (2) The I atom 2P3/2 to 2P1/2 branching ratio increases significantly in clusters relative to monomer. (3) TOF spectra were observed for I atoms originating from photodissociation of the cluster photoproduct I2. These observations are discussed in terms of a caging of I atoms that may either react or escape from the cluster.