The Spectrum of Lead Hydride

Abstract

From a lead arc in a hydrogen atmosphere at four to five atmospheres pressure, a "many-lined" spectrum in the region 5000-7000A due to PbH has been produced. Practically all of the lines have been assigned to ten bands constituting a ${}_{}{}^2{}_{}{}^{}\Sigma \to {}_{}{}^2{}_{}{}^{}\Sigma$ transition between an upper state of low stability and a stable ground state (${\omega }_e=1565.2\mathrm{}$, $B_e=4.972\mathrm{}$). Strong interaction with other states is evidenced by a very large spin-doubling ($\gamma =6.17\mathrm{}$) in the lower state and in the upper state by an unorthodox variation of ${B_v}^{*}$ with $v$, irregular spin doubling, a prominent failure of the Mecke rule and a sharp cut-off of levels at about $\frac{1}{3}$ volt above $K^{\prime }=0\mathrm{}$, $v^{\prime }=0\mathrm{}$.