Electronic ground state of Ni$_2^+$

TL;DR

This study experimentally determines the electronic ground state of Ni$_2^+$ using x-ray magnetic circular dichroism spectroscopy, revealing insights into its magnetic properties at cryogenic temperatures.

Contribution

First experimental determination of Ni$_2^+$ ground state and magnetic properties using advanced x-ray spectroscopy techniques.

Findings

Ni$_2^+$ has a $^{4}\

Magnetic dipole contribution is about 11% of the spin magnetic moment.

Homonuclear diatomic cations of 3d transition metals tend to have maximum spin magnetic moments.

Abstract

The $^{4}\Phi_{9/2}$ ground state of the Ni$_2^+$ diatomic molecular cation is determined experimentally from temperature and magnetic-field-dependent x-ray magnetic circular dichroism spectroscopy in a cryogenic ion trap, where an electronic and rotational temperature of $7.4 \pm 0.2$ K was reached by buffer gas cooling of the molecular ion. The contribution of the magnetic dipole term to the x-ray magnetic circular dichroism spin sum rule amounts to $7\, T_z = 0.17 \pm 0.06$ $\mu_B$ per atom, approximately 11 % of the spin magnetic moment. We find that, in general, homonuclear diatomic molecular cations of $3d$ transition metals seem to adopt maximum spin magnetic moments in their electronic ground states.