Comment on "Experimental Studies of Os^-: Observation of a Bound-Bound Electric Dipole Transition in an Atomic Negative Ion"

TL;DR

This paper critiques previous experimental measurements of Os^- ion binding energies, providing new theoretical calculations that clarify the true excited state and electron affinity of osmium, highlighting discrepancies in earlier data.

Contribution

The authors apply a recent complex angular momentum methodology to calculate Os^- ion binding energies, offering revised values that resolve previous experimental ambiguities.

Findings

Measured binding energy corresponds to an excited state, not the electron affinity.

Electron affinity of Os is determined to be 1.910 eV.

Previous experimental values are reassessed and clarified.

Abstract

Bilodeau and Haugan [1], using Infrared laser photodetachment spectroscopy, measured the binding energies (BEs) of the ground state (4Fe9/2) and the excited state (4Fe7/2) of the Os^- ion to be 1.07780(12) eV and 0.553(3) eV, respectively. These values are consistent with those calculated using Relativistic Configuration Interaction (RCI) calculations [2]. Here we have calculated the BEs for the ground state and the two excited states of the Os^- ion using our recent complex angular momentum (CAM) methodology [3] and obtained the BEs of 1.910, 1.230 and 0.224 eV, respectively (see Figure). We conclude that: 1) the measured value of 1.07780(12) eV corresponds to an excited state of Os^- and not to the EA of Os and 2) the EA of Os is 1.910 eV.