GAS-PHASE PHOTOLYSIS OF PENTAMETHYLDISILANE AT 206 NM

The photolysis of pentamethyldisilane, Me5Si2H, is characterized by a large number of decomposition processes of the excited molecule. Quant um yield determinations in the presence and absence of various scaveng ers support the occurrence of M2Si elimination (Phi=0.2) and Si-Si bon d breaking (Phi=0.14) as the two major decomposition processes. Other processes include the elimination of various silaethylenes and MeHSi. The quantum yield of these processes sum up to Phi=0.16. However, the most important pathway of the excited molecule is collisional deactiva tion (Phi=0.5). The material balance for the various silaethylenes is poor in the absence of traps but can be improved greatly in the presen ce of MeOH and is in agreement with computer simulations. Experiments with SF6 suggest that decomposition occurs mainly from the excited sta tes. (C) 1998 Elsevier Science S.A.