The Less Refrangible Bands in the Spectrum of Tin Monochloride

Abstract

Four groups of bands previously obtained by Jevons in a discharge through Sn${\mathrm{Cl}}_4$ vapor are now found also in streaming active nitrogen. Two groups, $\alpha$ and $\beta$, were previously classified as a ${}_{}{}^2{}_{}{}^{}S\to {}_{}{}^2{}_{}{}^{}P$ transition in SnCl; with the help of new measurements, and from an examination of the band structure, it is concluded that the other two groups, $\lambda 3500$ and $\lambda 3800$, are a ${}_{}{}^2{}_{}{}^{}D\to {}_{}{}^2{}_{}{}^{}P$ transition with the same ${}_{}{}^2{}_{}{}^{}P$ state as the $\alpha$ and $\beta$ bands. The chlorine isotope effect confirms the identity of the mitter as SnCl and confirms the vibrational quantum number assignments. The vibrational intensity distribution (intensity concentrated in $\Delta n=0\mathrm{}$ sequence) is in qualitative agreement with theory, for the ratio of ${{\omega }_0}^{\prime \prime }$ to ${{\omega }_0}^{\prime }$. An attempt was made to obtain analogous bands by introducing Sn${\mathrm{I}}_4$ vapor into active nitrogen, but no new bands were obtained.