The Infrared Spectrum ofH2Cl

The fundamental absorption band due to HCl molecules involving the heavier isotope of hydrogen has been observed, using a cell 700 cm long with gas at atmospheric pressure. It lies in the region of 4.8μ. Both ordinary HCl and samples enriched in ${\mathrm{H}}^2$ were examined. Nineteen lines have been measured in the band of ${\mathrm{H}}^2$ ${\mathrm{Cl}}^{35}$, and seventeen in the band of ${\mathrm{H}}^2$ ${\mathrm{Cl}}^{37}$. The estimated abundance of ${\mathrm{H}}^2$ relative to ${\mathrm{H}}^1$ is 1 to 35,000.