Kinetics and mechanism of the germane decomposition

The homogeneous gas‐phase thermal decomposition kinetics of germane have been measured in a single‐pulse shock tube between 950 and 1060 K at pressures around 4000 torr. The initial decomposition is GeH 4 → GeH 2 + H 2 in its pressure‐dependent regime, with log k   GeH   4 (4000)= 13.83 ± 0.78 – 50,750 ± 3570 cal/2.303 RT . RRKM calculations suggest that the high‐pressure Arrhenius parameters are log k GeH 4 (M → ∞) = 15.5 – 54,300 cal/2.303 RT . Extrapolations to static system pyrolysis conditions ( T ∼ 600 K, P ∼ 200 torr) give homogeneous reaction rates which are much slower than those observed, hence the static system pyrolysis of germane must be predominantly heterogeneous. Shock‐initiated pyrolysis reaction stoichiometry is 2 mol H 2 per mole GeH 4 , suggesting that the subsequent decomposition of germylene is essentially quantitative. Investigations of the hydrogen product yields for pyrolysis of GeD 4 in øCH 3 further indicate that the germylene decomposition reaction is mainly GeH 2 → H 2 + Ge, but that a small amount of reaction to H atoms may also occur.