Repulsive Potential Curves from Molecular Continuum–Continuum Emission III. He2(X 1Σg+)

A least‐squares iterative procedure is developed for deducing a repulsive (lower) potential curve from a known attractive (upper) potential curve and the observed continuum–continuum emission spectrum. The RKR curve for the $A^1{\Sigma }_u^{+}$ state of He₂ is used in conjunction with the 600‐Å band $\mathrm{(A–X)}$ data to determine that, for ${\mathrm{He}}_2{\mathrm{(X}}^1{\Sigma }_g^{+})$ , $$\text{V(R)\hspace{0.17em}=\hspace{0.17em}(202\hspace{0.17em}±\hspace{0.17em}10)}\exp \text{(−\hspace{0.17em}3.88\hspace{0.17em}±\hspace{0.17em}0.05)R, 1.3\hspace{0.17em}≤\hspace{0.17em}R\hspace{0.17em}≤\hspace{0.17em}2.4 Å.}$$ It is shown that the 600‐Å bands of ³He₂ can be predicted from those of ⁴He₂ without knowing the potentials. The Hopfield intensity distribution was recalculated to show that comparison with experiment still is hampered by lack of an accurate electronic transition moment function.