PHOTOCHEMISTRY OF ALKYL HALIDE DIMERS

Dimers and other small clusters of CH3I, C2H5I, i- and n-C3H7I, HI, CF3I, CH3Br, and C2H5Br formed in a supersonic expansion are irradiated at 248 and 193 nm and the halogen molecule product probed via laser induced fluorescence spectroscopy. Both dimers and larger clusters of RI (R = H, alkyl) excited at each wavelength yield I2 in its ground electronic state with very little internal energy. Clusters of CF3I and those containing alkyl bromides do not give halogen molecule products after excitation at either wavelength. A model for the dynamics in the dimer excited state which explains these results is presented.