Knowledge Bank

A discharge through helium containing a little phosphorus in a hollow cathode discharge tube has been found to emit a number of new bands between 3400 and 9000 \AA. These bands have been photographed with a 35 ft. grating spectrograph and their rotational and vibrational structures studied. Analysis of the 3900-4400 \AA bands show that they arise from a $\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}\Sigma u+-2\Sigma g+$ transition of the $P2+$ molecule. Two lower state progressions have been analyzed but the vibrational numbering is as yet unknown. A second band system has been found in the region 3400-3850 \AA and, on the basis of an incomplete analysis, has been assigned to a $\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}\Pi -2\Pi$ transition of $P2+$. When a small amount of hydrogen was added to the gas in the discharge, three hydride bands were found at 3648 \AA, 3850 \AA, and 4227 \AA. From a preliminary study of the bands, it appears probable that these bands arise from a $\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}A-2\Pi$ transition of $PH+$.