Multiphoton dissociation of Ga(CH3)3

Abstract

UV and visible multiphoton dissociation (MPD) processes of Ga(CH3)3 have been investigated by time-resolved detection of Ga(4 2PJ ) (J=1/2, 3/2) and Ga(5 2S1/2) following pulsed laser photolysis in a low pressure gas cell, and by mass spectrometric detection of ionic photofragments in a molecular beam. The relative abundances of neutral and ionic fragments were monitored as a function of photolysis wavelength and flux. Measurements of the anisotropy of the velocity distribution and the average kinetic energy of nascent Ga(4 2PJ ) are also reported. Under conditions of moderate photolysis flux (≂108 W cm−2), MPD of Ga(CH3)3 in the wavelength range 420–520 nm produced mainly neutral fragments, including Ga(4 2PJ ) and a metastable molecular fragment which is identified as GaCH3. Photolysis at 222 nm produced GaCH3 to the exclusion of Ga(4 2PJ ), or primarily ionic fragments at relatively high flux. At 308 nm, ionic Ga(CH3)+n species were produced in relatively high yield even in the limit of low photolysis flux. The mechanisms of MPD and MPI of Ga(CH3)3 are discussed with reference to simple rate equations models.