Absorption Spectrum of H2 in the Vacuum-uv Region. II. Rydberg Series Converging to the First Six Vibrational Levels of the H2+ Ground State

The absorption spectrum of H₂ at liquid‐nitrogen temperature has been further investigated with a 6.65‐m vacuum spectrograph in the 800–600‐Å region. Eleven distinct groups, each consisting of 8–30 absorption lines, have been observed at wavelengths converging to the levels $\text{υ\hspace{0.17em}=\hspace{0.17em}0–5}$ of the H₂⁺ ground state. Evidently these individual groups are Rydberg series. Consideration of l‐uncoupling effects permits these series to be assigned as $\text{R(0)}$ , $\text{R(1)}$ , and $\text{Q(1)}$ series in $\mathrm{np\pi \hspace{0.17em}\leftarrow \hspace{0.17em}X}$ transitions and as $\text{R(0)}$ series in $\mathrm{np\sigma \hspace{0.17em}\leftarrow \hspace{0.17em}X}$ transitions. A new value of the ionization energy of H₂, 124 418.4 ± 0.6 cm⁻¹, has been obtained from Rydberg series converging to the $\text{υ\hspace{0.17em}=\hspace{0.17em}0}$ level of the H₂⁺ ground state.