Direct Observation of High-Spin States in Manganese Dimer and Trimer Cations by X-ray Magnetic Circular Dichroism Spectroscopy in an Ion Trap

TL;DR

This study directly observes high-spin states in Mn$_2^+$ and Mn$_3^+$ cations using X-ray magnetic circular dichroism spectroscopy, revealing their magnetic moments and electronic structure in an ion trap.

Contribution

It provides the first direct spectroscopic evidence of high-spin states and magnetic moments in Mn dimer and trimer cations, elucidating their electronic coupling mechanisms.

Findings

Localized magnetic moments of 5 μ_B per Mn atom.

Total magnetic moments of 11 μ_B for Mn$_2^+$ and 16 μ_B for Mn$_3^+$.

High-spin states are mediated by indirect exchange via a delocalized valence electron.

Abstract

The electronic structure and magnetic moments of free Mn$_2^+$ and Mn$_3^+$ are characterized by $2p$ x-ray absorption and x-ray magnetic circular dichroism spectroscopy in a cryogenic ion trap that is coupled to a synchrotron radiation beamline. Our results show directly that localized magnetic moments of 5 $\mu_B$ are created by $3d^5 (^6\mathrm{S})$ states at each ionic core, which are coupled in parallel to form molecular high-spin states via indirect exchange that is mediated in both cases by a delocalized valence electron in a singly-occupied $4s$ derived orbital with an unpaired spin. This leads to total magnetic moments of 11 $\mu_B$ for Mn$_2^+$ and 16 $\mu_B$ for Mn$_3^+$, with no contribution of orbital angular momentum.