Knowledge Bank

The absorption spectrum of $H2$ at liquid nitrogen temperature was further investigated with a 6.5 m vacuum spectrograph in the $600-800\backslash AA$ region. Five distinct groups, each consisting of from 11 to 30 lines, were observed at wavelengths corresponding to levels $v=0,1,2,4,$ and 5 of $H2+$. Apparently, individual groups form Rydberg series. They converge to $124647(v=0),126819(v=1),128864(v=2),132575(v=4)$, and $132270cm-1(v=5)$. These values are very close to $K=3$ level in the respective vibrational levels of $H2+$ if the lower level is assumed to be the $K=1,v=0$ of the $H2$ ground state. Upon consideration of l-uncoupling these groups may be attributed to appropriate R(1) Rydberg series in np $\pi \leftarrow X$ transitions.