Knowledge Bank

The high-resolution infra-red spectrum of $GeH4$ in the region 2020 to $2200cm-1$ has been analysed. Most of the observed lines have been assigned to transitions of the $v3$ and $v1$ bands of the five naturally-occuring isotopic species. The spectrum has been fitted by diagonalizing the $v3=1$ and $v1=1$ hamiltonians coupled by the dominant vibration-rotation interaction term. For each isotopic species, about one hundred transitions have been fitted with an overall standard deviation of $0.006cm-1$, using only ten adjustable parameters. The five sets of parameters obtained are consistent with the expected isotope effects.