Some Peculiar Hydrogen Bands

Abstract

Photographs of the secondary spectrum of hydrogen as excited by an electrodeless ring discharge were taken at various pressures in the range 0.08 to 0.001 mm. A number of lines were found to be much more intense at low pressures than at high pressures. The more prominent of these were arranged into a band with $P$, $Q$ and $R$ branches corresponding to a $\Pi \to \Sigma$ type electronic transition; this band was assumed to be a 0→0 band. The majority of the remaining lines were tentatively arranged into three more bands which appeared to be the 1→0, 0→1 and 1→1 bands corresponding to the same $\Pi \to \Sigma$ electronic transition. The values of the moments of inertia are ${I_0}^{\prime }=3.8\mathrm{}\times {10}^{-40\mathrm{}}$, ${I_1}^{\prime }=5.5\mathrm{}\times {10}^{-40\mathrm{}}$, ${I_0}^{\prime \prime }=2.0\mathrm{}\times {10}^{-40\mathrm{}}$ and ${I_1}^{\prime \prime }=2.3\mathrm{}\times {10}^{-40\mathrm{}}$. The corresponding values of the nuclear separation "$r$" are ${r_0}^{\prime }=2.14\mathrm{}\times {10}^{-8\mathrm{}}$ cm, ${r_1}^{\prime }=2.57\mathrm{}\times {10}^{-8\mathrm{}}$ cm, ${r_0}^{\prime \prime }=1.55\mathrm{}\times {10}^{-8\mathrm{}}$ cm, and ${r_1}^{\prime \prime }=1.66\mathrm{}\times {10}^{-8\mathrm{}}$ cm. The emitter of these bands is thought to be either ${\mathrm{H}}_2^{+}$ or doubly excited hydrogen.