Absolute numbering of asymptotic vibrational levels of diatomic molecules from cold physics experiments

TL;DR

The paper introduces a straightforward isotope-shift-based method for determining the absolute vibrational numbering of near-dissociation levels in diatomic molecules, applicable with minimal data from cold physics experiments.

Contribution

It provides a new simple technique for vibrational level numbering using limited isotope shift measurements, aligning well with complex potential curve fitting results.

Findings

Method accurately predicts vibrational levels near dissociation.

Applicable with measurements from only two isotopologues.

Results validated on ultracold Yb2, CsYb, RbSr, and RbYb molecules.

Abstract

We present a simple method for determination of absolute vibrational numbering of isolated near dissociation levels in diatomic molecules, usually observed in cold physics experiments. The method is based on the isotope shift and works even when energies of only two levels from one isotopologue and one level from another isotopologue have been measured. It is demonstrated on data from recently reported precise measurements of binding energies of levels lying close to the dissociation limits in ultracold Yb2, CsYb, RbSr and RbYb molecules. Its predictions agree with these of much more elaborate multi-isotope potential curve fitting. PACS numbers: 31.50.Bc, 33.20.Kf, 33.20.Vq, 33.50.Dq