Barium Hydride Band Spectra in the Near Infrared

A BaH band system with principal heads at 8924A and 9017A degraded to the red is ${}_{}{}^2{}_{}{}^{}\Sigma \to {}_{}{}^2{}_{}{}^{}\Sigma$ with the same lower ${}_{}{}^2{}_{}{}^{}\Sigma$ as for the ${}_{}{}^2{}_{}{}^{}\Pi \to {}_{}{}^2{}_{}{}^{}\Sigma$ BaH bands in the visible red region. For the upper ${}_{}{}^2{}_{}{}^{}\Sigma$ state $B_0=3.232\mathrm{}$, $D_0=-1.323\mathrm{}\times {10}^{-4\mathrm{}}$ and ${\gamma }_0=-4.84\mathrm{}$. This very large spin doubling indicates interaction with a near-lying lower ${}_{}{}^2{}_{}{}^{}\Pi$ state which computation shows to be the probable upper state of another BaH band observed on the long wave-length side of 10,052A. The nature of the electron configurations in the several BaH states is discussed.