THE a-X ELECTRONIC BAND SYSTEM OF SeO IN THE INFRARED REGION AT $1.8\;\mu$m

Abstract

The emission spectrum of the SeO molecule excited in a discharge tube by a microwave generator and recorded at low resolution with an infrared spectrometer equipped with a lead sulphide detector revealed the existence of a brief band system in the region $6470 - 5540\;cm^{-1}$. The system consists of $\Delta v = 0$ and +1 sequences and is assigned to the transition $a2 - X_{2}1$ (X being the case - c $^{3}\Sigma^{-}$ ground state of the SeO molecule). The transition $a2 - X_{1} 0$ is forbidden because of the selection rule $\Delta \Omega=0, \pm 1$. An approximate value of the rotational constant $B_{o}$ of state a is obtained from the observed separation between the Q and R heads of the 0-0 band and the known value of $B_{o}$ of state $^{X} 1$ The derived molecular parameters of state a are: $v_{00}=5566.7\;cm^{-1}$, $\Delta G(\frac{1}{2}) = 883.3\;cm^{-1} B_{0} = 0.45_{6}\;cm^{-1}$. The value of $B_{o}$ of a is in reasonable agreement with one obtained form a previous study of the gas phase electron spin resonance spectrum of $SeO^{2}$ Molecular constants of all the known electronic states of SeO will also b discussed.