THE 3500 {\AA} EMISSION BAND SPECTRUM OF XeF

Author Institution: Department of Chemistry, Vanderbilt UniversityElectron-beam excitation of $Xe/F_{2}$ mixtures at moderate pressures ($> 1/2$ atm) gives rise to an emission band system attributed to XeF. The vibrational analysis of this spectrum presently encompasses the first 6 vibrational levels of both electronic states, and yields $\omega_{e}^{\prime\prime} = 305$ $cm^{-1}$, $D_{e}^{\prime\prime}$ (to ions) = 42 $600 cm^{-1}, \omega_{e}^{\prime} \approx 200$ $cm^{-1}, D_{e}^{\prime} \mathop{>}{\sim} 600 cm^{-1}$. Band profile and Franck-Condon calculations indicate the ground-state inter-nuclear distance $R_{e}^{\prime\prime} is \sim 0.18$ \AA smaller than $R_{e}^{\prime}$. The great anharmonicity of the $^{2}\Sigma^{+}$ ground state accounts for the occurrence of both red- and violet-degraded spectral bands. The prominent features near 3510 \AA and 3530 \AA, on which lasing has been achieved, are respectively the 0-0 (with strong overlapping emission from 1-2) and 0-1 bands. A rotational analysis of this spectrum is in progress