ENERGY PARTITIONING IN PHOTODISSOCIATION OF METHYL, ETHYL AND N-PROPYL IODIDES AT 304 NM

The energy partitioning in photodissociation of n-alkyl iodides has be en studied by state-selective photofragment translational spectroscopy combined with a pulsed molecular beam at 304 nm. Translational energi es of photofragments are obtained by analyzing the time-of-flights of two product channel iodine atoms, i.e., I(P-2(3/2)) and I(P-2(1/2)) f or CH3I, C2H5I and C3H7I. The average energy disposed into the interna l mode (E(int)) of alkyl radicals has shown an increasing tendency fro m 17% for the I channel of CH3I to 53% for the I channel of n-C3H7I a nd is estimated to further increase to 76% for the I channel of C4H9I . The methyl radical in CH3I photolysis has shown the vibrational exci tation in its umbrella mode. The distribution peaks have appeared at n u = 2 for I and nu = 4 for I product channels, respectively. The obse rved results are compared with a classical impulsive description dynam ics. The energy partitioning is found to be very little dependent on t he excitation wavelength for photodissociation all over the A-band reg ion.