Photoelectron Spectroscopy and Density Functional Theory Calculations of Binary V_nC_3^0/- (n=1-6) Clusters

Transition metal carbides have been shown to exhibit good catalytic performance that depends on their compositions and morphologies, and understanding such catalytic properties requires knowledge of their precise geometry, determination of which is challenging, particularly for clusters formed by multiple elements. In this study, we investigate the geometries and electronic structures of binary V_nC_3^- (n=1-6) clusters and their neutrals using photoelectron spectroscopy and theoretical calculations based on density functional theory. The adiabatic detachment energies of V_nC_3^-, or equally, the electron affinities of V_nC_3, have been determined from the measured photoelectron spectra. Theoretical calculations reveal that the carbon atoms become separate when the number of V atoms increases in the clusters, i.e., the C-C interactions present in small clusters are replaced by V-C and/or V-V interactions in larger ones. We further explore the composition dependent formation of cubic or cube-like structures in 8-atom V_nC_m (n+m=8) clusters.