Structure of Magnetic Lanthanide Clusters from Far-IR Spectroscopy: Tb (n = 5-9)

TL;DR

This study determines the structures of small terbium clusters (n=5-9) in the gas phase using far-IR spectroscopy and DFT calculations, revealing bonding primarily involves 5d and 6s electrons with 4f electrons playing an indirect role.

Contribution

The paper provides the first structural identification of small terbium clusters using vibrational spectroscopy combined with DFT, highlighting the bonding nature in lanthanide clusters.

Findings

Structures of Tb(n=5-9) clusters are similar to transition metal systems.

Bonding involves 5d and 6s electrons, with 4f electrons having an indirect effect.

DFT with 4f-in-core ECP accurately reproduces experimental spectra.

Abstract

Small lanthanide clusters have interesting magnetic properties, but their structures are unknown. We have identified the structures of small terbium cluster cations Tb (n = 5-9) in the gas phase, by analysis of their vibrational spectra. The spectra have been measured via IR multiple photon dissociation of their complexes with Ar atoms in the 50-250 1/cm range with an infrared free electron laser. Density functional theory calculations using a 4f-in-core effective core potential (ECP) accurately reproduce the experimental far-IR spectra. The ECP corresponds to a 4f85d16s2 trivalent configuration of terbium. The assigned structures are similar to those observed in several other transition metal systems. From this, we conclude that the bonding in Tb clusters is through the interactions between the 5d and 6s electrons, and that the 4f electrons have only an indirect effect on the cluster structures.