Ab initio calculation of the he2 a1Σu+k←x1Σg+ absorption spectrum

Shaul Mukamel, Uzi Kaldor

Research output: Contribution to journalArticlepeer-review


The absorption spectrum of helium gas near 600 Å, assigned to the A1Σu+K←X1Σg+ transition in He2, is calculated at 77 K. The excited state potential is taken from a recent ab initio calculation. The theoretical spectrum shows well-defined bands, corresponding to different vibration levels of the A state, with diffuse rotational structure, in agreement with experiment. Fairly good quantitative agreement with Tanaka and Yoshino's measured spectrum is obtained, except for the somewhat too large separation between calculated vibrational bands, probably due to the theoretical potential for the A state rising too steeply at small inter-nuclear separation. Rotational constants derived from the calculated and experimental spectra are in good agreement. It is shown that they are significantly smaller than actual rotational constants of the upper state.

Original languageEnglish
Pages (from-to)291-295
Number of pages5
JournalMolecular Physics
Issue number2
StatePublished - Aug 1973


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