Dissociation Energies of He2+(X2Σu+) and He2(A1Σu+)

Abstract

The configuration-interaction method is applied to calculate the dissociation energy of ${{\mathrm{He}}_2}^{+}\left(X^2{{\Sigma }_{\mathrm{u}}}^{+}\right)$, yielding a rigorous lower bound of 2.454 eV and a best value of 2.469 ±0.006 eV. These results are used, in combination with available spectroscopic data on vibrational states of the $A^1{{\Sigma }_u}^{+}$ state of ${\mathrm{He}}_2$, to unequivocally make an assignment of 2.549±0.012 eV for the apparent dissociation energy and to predict a barrier height of 0.080±0.018 eV for this state.