Rotational Analysis of Ultraviolet Bands of Silicon Monoxide

From measurements on silicon arc spectrograms a rotational analysis has been made of the (0,1), (0,2), (0,3), (0,4) and (1,4) bands of the ultraviolet band system of silicon monoxide (SiO). The bands were found to be due to a ${}_{}{}^1{}_{}{}^{}\Pi \to {}_{}{}^1{}_{}{}^{}\Sigma$ transition as was expected by analogy with the fourth positive bands of CO. Among the constants obtained from the analysis are A number of perturbations of the $Q$ branch lines were observed. Some conclusions were reached as to the nature of the perturbing levels. From measurements of band heads of this system made by Jevons and the results of the present analysis the following equation was obtained for the band origins: $\{{\nu }_0=,42835.3+851.51(v^{\prime }+\frac{1}{2})-6.143\mathrm{}{(v^{\prime }+\frac{1}{2})}^2+\}\{0.0437{(v^{\prime }+\frac{1}{2})}^3-1242.03(v^{\prime \prime }+\frac{1}{2})+\}\{6.047{(v^{\prime \prime }+\frac{1}{2})}^2-0.00329\mathrm{}{(v^{\prime \prime }+\frac{1}{2})}^3.\}$