The infrared spectra of gaseous CH3GeH3, CD3GeH3, and CH3GeD3were observed in the range 4000ndash;400 cmmdash;1. The 12 fundamental frequencies for each molecule are assigned to normal modes and the spectra are discussed in some detail. Tellermdash;Redlich producthyphen;rule ratios support the assignments. The height of the barrier hindering internal rotation was found from measurements on twelve combination bands involving the torsional modes to have an average value of 1270 cal/mole. The torsional force constant was estimated to be 0.31times;10mdash;12erg/rad. The corresponding barrier height and torsional force constant for methylsilane were estimated to be 1715 cal/mole and 0.44times;10mdash;12erg/rad, respectively, from published data.Analyses of the rotational structures of ngr;7ndash;10and of ngr;12and 2ngr;12in the spectrum of CH3GeH3and of ngr;7ndash;10and ngr;12in the spectrum of CD3GeH3afforded values for the band origins, certain rotational constants and zgr;7ndash;12for both molecules.
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