Knowledge Bank

Ninety-four previously unobserved transitions of the five isotopic species of hydrogen selenide have been measured in the 100-600 GHz region of the microwave spectrum. Watson’s reduced centrifugal distortion Hamiltonian has been used to analyze this data in conjunction with the infrared combination differences of $Hill.1$ The energy levels and spectral constants which result are in good agreement with both the infrared and microwave data. The less abundant $\mathrm{<mrow\; data-mjx-texclass="ORD">76</mrow>}Se$, $\mathrm{<mrow\; data-mjx-texclass="ORD">77</mrow>}Se$, and $\mathrm{<mrow\; data-mjx-texclass="ORD">82</mrow>}Se$ species, for which no infrared combination differences are available, were analyzed primarily on the basis of the observed microwave transitions. Isotopic comparisons have been made and the effects of the symmetry (K $\approx$ 0.82) on the centrifugal distortion analysis considered. For $H2$$\mathrm{<mrow\; data-mjx-texclass="ORD">80</mrow>}Se$ the rotational and $P4$ distortion constants are (in MHZ): A = 244 099.89, B = 232 561.95, C = 116 874.93, $\Delta j=34.950,\Delta JK=-118.119,\Delta K$ = 88.1173, $\delta j=-2.12091,\delta K-461.0394$.