Knowledge Bank

Ten transitions in the Q branch of the distortion moment spectrum of $GeH4$ in its ground vibronic state have been measured between 8 and 24 GHz using a sensitive 1 kHz Stark modulated microwave $spectrometer1$ Both the widths and the frequencies of the observed lines are consistent with the assumption that isotopic effects are negligible. On the basis of this assumption isotopically averaged values have been obtained for one quartic, two sextic and three octic tensor centrifugal distortion constants. The current results will be discussed in the light of the spectra obtained recently by the infrared-microwave double resonance $method2$