Beryllium Hydride Band Spectra

Abstract

Two new band systems appear in a Be arc in hydrogen, one in the green from 4800A to 5120A, the other from 3700A to beyond 2200A in the ultra-violet. Measurements of the bands of both systems at high dispersion are reported, and the quantum analysis is given. The green band group belongs probably to the ${}_{}{}^2{}_{}{}^{}P\to {}_{}{}^2{}_{}{}^{}S$ class due to BeH molecules. It consists of the 0-0, 1-1, 2-2, etc., bands, degrading to the violet, but all branches exhibit a marked shift to the red for $j>\mathrm{}30\mathrm{}$. The analysis gives ${I_0}^{\prime }=2.6833\mathrm{}\times {10}^{-40\mathrm{}}$ gm ${\mathrm{cm}}^2$ and ${I_0}^{\prime \prime }=2.7212\mathrm{}\times {10}^{-40\mathrm{}}$ gm ${\mathrm{cm}}^2$ for the moments of inertia, ${r_0}^{\prime \prime }=1.35\mathrm{}\times {10}^{-8\mathrm{}}$ cm, ${{\omega }_0}^{\prime }=2053.4\mathrm{}$, ${{\omega }_0}^{\prime \prime }=2025.7\mathrm{}$. The ultra-violet system consists of singlet $P$, $R$ branch bands degrading to the red, the equation for the zero-points being $\nu =39059+1460.5\mathrm{}{n}^{\prime }-14.5\mathrm{}{n}^{\prime 2}-2182.0\mathrm{}{n}^{\prime \prime }+41.0\mathrm{}{n}^{\prime \prime 2}$. For this system, ${I_0}^{\prime }=3.85\mathrm{}\times {10}^{-40\mathrm{}}$ gm ${\mathrm{cm}}^2$ and ${I_0}^{\prime \prime }=2.50\mathrm{}\times {10}^{-40\mathrm{}}$ gm ${\mathrm{cm}}^2$, ${r_0}^{\prime \prime }=1.29\mathrm{}\times {10}^{-8\mathrm{}}$ cm. A discussion of the probable electronic transition for the ultra-violet bands is included.