J. Phys. Chem. 1994,98, 2095-2100
Time-Resolved Infrared Absorption Spectroscopy of 193"
2095
Photodissociation of Diethylzinc
Paul F. Seidler IBM Thomas J . Watson Research Center, P.O. Box 218, Yorktown Heights, New York 10598 Received: September 24, 1993: In Final Form: December 16, 19939
The products of 193-nm photolysis of diethylzinc are monitored by time-resolved infrared absorption in the range 2100-3200 cm-I. The organic photofragments are assigned as highly vibrationally and rotationally excited free ethyl radicals. No evidence is found for prompt generation of ethane, ethene, or butane as primary photoproducts, suggesting that the only important photodissociation mechanism is simple metal-alkyl bond homolysis.
Introduction The photochemistry of metal-alkyl complexes is receiving increased attention because of the importance of these species to metal deposition processes, particularly those used in the microelectronics industry. This paper describes a study of the photodissociation of diethylzinc,a compound employed in a variety of thermal and photoinduced chemical vapor depositionprocesses, includingthe fabricationof ohmic contacts,use as a p-type dopant, and manufacture of 11-VI light-emitting or light-sensitive devices.I4 Laser-driven methods for producing metal from group 12 dialkyl complexes commonly exploit excitation of states accessible with 248- and 193-nm excimer radiation.5 Like photolyses of many organometallic species in the gas phase, absorption of a single UV photon leads to scission of more than one metal-ligand bond, and elucidation of the mechanism and energy disposal in these reactions has been the subject of several investigations. Photodissociation is only well understood, however, for the dimethyl complexes of group 12 metals. Reaction is thought to proceed by sequential metal-alkyl bond homolysis. Monomethylmetal and free methyl radicals are formed rapidly (
