Note on the Interpretation of CertainΔ2,Π2Bands of SiH

Abstract

It is shown that Jackson's ${}_{}{}^2{}_{}{}^{}\Delta$, ${}_{}{}^2{}_{}{}^{}\Pi$ SiH bands have a regular ${}_{}{}^2{}_{}{}^{}\Pi$ state and thus are closely analogous to the $\lambda 4300$ bands of CH. The orbit-spin coupling coefficient $A$ is determined for the ${}_{}{}^2{}_{}{}^{}\Pi$ state of SiH and shown to agree closely with $A$ of the ${}_{}{}^3{}_{}{}^{}P$ state of the Si atom, from which the ${}_{}{}^2{}_{}{}^{}\Pi$ molecular state is supposed to be derived. This is a new example of a relation which seems to be universal. Another new example of the same relation, found in BeH, is also cited.—The coefficients $A$ and $B$ of the ${}_{}{}^2{}_{}{}^{}\Delta$ state and $B$ of the ${}_{}{}^2{}_{}{}^{}\Pi$ state of SiH are also discussed.