INFRARED DIODE-LASER STUDY OF PRODUCT ENERGY-DISTRIBUTION IN THE F+OCS REACTION

The reaction F+OCS-->SF+CO has been investigated by using infrared dio de laser spectroscopy to probe both reaction products SF((2) Pi(3/2,1/ 2)) and CO. Fluorine atoms were prepared by pulsed CO2 laser photolysi s of SF6 in the presence of OCS. Time-resolved absorption spectra, inc luding many rovibrational lines of SF in the nu = 4-3, 3-2, 2-1, and 1 -0 bands and those of CO in the nu = 2-1 and 1-0 bands, were observed to derive nascent internal energy distributions of the reaction produc ts. The vibrational and rotational energy distributions obtained were Boltzmann-like, and no clear evidence for population inversion was fou nd. Energy partitioning to vibrational modes of SF and CO was only 8 a nd 0.7% of total available energy (approximate to 3500 cm(-1)), and th at to rotational modes of SF and CO was 28% in both cases. These value s were not so far from a statistical prior distribution (13, 2.8, 23, and 23%, respectively), indicating that the reaction F+OCS proceeds vi a an intermediate such as FSCO radical, which may descompose to SF and CO before complete energy randomization. No preference was observed f or Lambda-doubling components of SF, while spin-orbit component popula tion (2) Pi(1/2)/(2) Pi(3/2) was 0.26, which was colder than the prior distribution ((2) Pi(1/2)/(2) Pi(3/2) = 0.68).