Quantum Analysis of the Beryllium Oxide Bands

Abstract

New measurements of the structure lines in the (0, 0), (1, 1), (0, 1), (1, 2), (1, 0) and (2, 1) bands of the visible BeO system are reported. Each band has $P$ and $R$ branches of almost equal intensity, the lines of which are strictly single. There is probably but one missing line at the origin. This structure characterizes the system as ${}_{}{}^1{}_{}{}^{}S\to {}_{}{}^1{}_{}{}^{}S$, the odd multiplicity agreeing with the even number of electrons in neutral BeO. The rotational terms are investigated by the combination principle, and can be represented by $F\left(j\right)=Bj(j+1\mathrm{})+D{\mathrm{}\left[j\right(j+1\mathrm{}\left)\right]}^2+\cdots$ with $j$ integral as required for ${}_{}{}^1{}_{}{}^{}S$ states. One perturbation is found, consisting of a displacement of the line $R\left(49\right)\mathrm{}$ in the (1, 0) band by 0.45 ${\mathrm{cm}}^{-1\mathrm{}}$ toward lower frequencies, with no sign of doubling. The following equation is obtained for the null-lines: $v_0=21,254.05+1370.81(n^{\prime }+\frac{1}{2})-7.76\mathrm{}{(n^{\prime }+\frac{1}{2})}^2-1487.45(n^{\prime \prime }+\frac{1}{2})+11.87\mathrm{}{(n^{\prime \prime }+\frac{1}{2})}^2$.