The Spectrum of Indium Oxide

A rather complex spectrum of InO lying between the two In resonance lines at 4102A and 4511A is described. Most of the band heads are assigned to a ${}_{}{}^2{}_{}{}^{}\Pi \to {}_{}{}^2{}_{}{}^{}\Sigma$ system with the frequencies of the main ($R_2+Q_2?$) heads given by the formula $\nu =23,595.10+626.66(v^{\prime }+\frac{1}{2})-3.40\mathrm{}{(v^{\prime }+\frac{1}{2})}^2-703.09(v^{\prime \prime }+\frac{1}{2})+3.71\mathrm{}{(v^{\prime \prime }+\frac{1}{2})}^2+0.285\mathrm{}{(v^{\prime \prime }+\frac{1}{2})}^3$. ${\nu }_e$ for the other spin component is at 23,033.10. The large cubic term causes rapid convergence of the few band sequences giving rise to prominent "tail" bands.