Accurate dissociation energies from rotational predissociation and long-range forces: B 1Π LiH

Abstract

A new approach for determination of accurate dissociation energies from experimental predissociation data and the calculated long‐range potential is described. In this case long‐range predissociation in the rotational manifold of only a single vibrational level is required to yield a precise dissociation limit. The case of B ¹Π LiH is considered in detail and a dissociation limit of 34 492.5 ± 0.5 cm⁻¹ is obtained, 2.5 cm⁻¹ lower and 4 times more precise than the best previous result. Also presented is a reasonably good representation of the potential energy curve for the B ¹Π LiH molecule, constructed by an isotopically combined Rydberg‐Klein‐Rees method based on the concept of mass‐reduced quantum numbers: $\mathrm{\eta \; \equiv \; [\nu +}\frac{1}{2}\mathrm{]/}\sqrt{\mu }$ and ξ≡J(J + 1)/μ.