Experimental and theoretical studies of excited states of H2 observed in the absorption spectrum: III. The 5pσ, 6pσ and 7pσ 1Σu+ states

•Level energies and absolute line intensities measured in H2 absorption.•Calculation from first principles of perturbed spectra in H2.•Numerous new spectral lines observed and assigned.•Vibrational progressions followed up to high quantum numbers.•Quantitative agreement between observations and ab initio theory.

A comprehensive study of the absorption transitions leading to the 5pσ, 6pσ and 7pσ Rydberg states of H2 is presented which includes rovibronic level energies, line intensities and widths. The analysis of the experimental data is carried out with the help of multichannel quantum defect theory implemented here purely from first principles. Numerous new assignments are reported and some older assignments are corrected. The overall agreement between experiment and theory is very good. In particular, absorption line (resonance) energies are reproduced to within 1 cm−1.

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