THEORY OF PURE-ROTATIONAL SPECTRA OF $OsO_{4}$

Abstract

Osmium tetroxide is one of a class of tetrahedral $XY_{4}$ molecules predicted to have pure-rotational transitions in the vibronic ground state, $Os^{16}O_{4}$ is unusual because its identical nuclei have spin zero. Consequently only rotational levels of symmetry A exist by virtue of the pauli exclusion principle. On the basis of new, very high-resolution ($\Delta \nu \approx 0.0007$ $cm^{-1}$, Doppler limited) spectra of the vibration-rotation fundamental at $961\, cm^{-1}$ obtained by McDowell et al. using a tunable semiconductor diode laser, it is possible to characterize the pure-rotational spectra of $OSO_{4}$ quantitatively. Calculated estimates of the line intensities and positions will be presented. Competing effects will be discussed. Possible experimental configurations be will considered.