Potential curves from continuous spectra: He2X1Σg+andA1Σu+

Abstract

Continuous electronic spectra of diatomic molecules can often be related to the associated potential curves. It is demonstrated that the local nature of continuous spectra may greatly facilitate inversion of the spectra to obtain ground and excited state potential curves. All of the observed continuous spectra related to transitions between the X and A states of the helium diatomic molecule are re-examined with the goal of determining accurate potential curves for the two states. It is shown that the excited state dissociation energy is 2·50±0·03 eV and that the MDD-1 potential proposed by Bruch and McGee is the preferred choice to represent the ground state interaction. Also, the mean cross section at 300 K for the destruction of a 21 S helium atom by collision-induced emission is evaluated and found to be 2·8 × 10-20 cm2 in agreement with the measurements of Phelps.