| Abstrakt: |
The gas phase ultraviolet (UV) excimer laser induced photolysis of the gallium-alkyls Ga(t-C4H9)n- (CH3)3-n (n=0, 1, 2, 3) was studied, using photolysis wavelengths of 308, 248, and 193 nm. The photofragments Ga, GaH, and GaCH3 were detected by laser ionization time-of-flight mass spectroscopy, while the hydrocarbon products CH4, C2H6, HC(CH3)3 and H2C=C(CH3)2 were identified using Fourier transform infrared (FTIR) spectroscopy. The formation of the GaH photofragment, and a high olefin-to-alkane product ratio, for Ga(t-C4H9)2(CH3) and Ga(t-C4H9)3 are interpreted to indicate a ß-hydrogen elimination process. However, ß-hydrogen elimination only occurs after fission of the weakest Ga-C bond, thus no ß-hydride elimination is observed for Ga(t-C4H9)(CH3)2. Detection of C2H6 for Ga(CH3)3 and Ga(t-C4H9)(CH3)2, but not for Ga(t-C4H9)2(CH3), shows that under our experimental conditions the formation of ethane is as a result of the reductive elimination of the methyl groups, and is not due to the recombination of two free methyl radicals. |
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