Predicting quasibound states of negative ions

TL;DR

This paper presents a high-precision theoretical method for accurately predicting quasibound states in negative ions, validated by experimental data on La$^-$ and applicable to various ions.

Contribution

The authors developed a novel theoretical approach that accurately predicts quasibound states, validated by experiment, and applicable to a wide range of negative ions.

Findings

All observed resonances in La$^-$ were identified

A new resonance peak was predicted and experimentally confirmed

The method enables large-scale generation of atomic transition data

Abstract

We demonstrated the accurate prediction of a quasibound spectrum of a negative ion using a novel high-precision theoretical approach. We used La$^-$ as a test case due to a recent experiment that measured energies of 11 resonances in its photodetachment spectrum attributed to transitions to quasibound states [C. W. Walter et al., PRA, in press (2020); arXiv:2010.01122]. We identified all of the observed resonances, and predicted one more peak just outside the range of the prior experiment. Following the theoretical prediction, the peak was observed at the predicted wavelength, validating the identification. The same approach is applicable to a wide range of negative ions. Moreover, theory advances reported in this work can be used for massive generation of atomic transition properties for neutrals and positive ions needed for a variety of applications.