Anion photoelectron spectroscopy and density functional theory study of TM2Sin− (TM = V, Cr; n = 14–20) clusters

• Published in: Physical chemistry chemical physics : PCCP Vol. 24; no. 30; pp. 18321 - 18330
• Main Authors: Wang, Kai, Guang-Jia Yin, Ze-Zhao Jia, Lin, Miao, Moro, Ramiro, Bernd von Issendorff, Ma, Lei
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 03.08.2022
• Subjects: Anions; Atomic properties; Chromium; Clusters; Density functional theory; Electronic properties; Fullerenes; Genetic algorithms; Magnetic moments; Mathematical analysis; Photoelectron spectroscopy; Photoelectrons; Silicon; Spectrum analysis; Transition metals
• ISSN: 1463-9076; 1463-9084; 1463-9084
• DOI: 10.1039/d2cp01649d

We investigated the structural evolution and electronic properties of medium-sized silicon cluster anions doped with two transition metal atoms, TM2Sin− (TM = V, Cr; n = 14–20), by using mass-selective anion photoelectron spectroscopy combined with density functional theory (DFT) calculations. Putative ground state structures of these clusters were obtained by using a genetic algorithm coupled with the DFT calculations. It was found that the two TM atoms tend to form a TM–TM bond, which – except for V2Si19− – is shorter than the nearest neighbour distance in the crystalline state of the respective metals. The V2Sin− clusters with n = 14 to 17 exhibit structures based on a silicon hexagonal antiprism, while the larger ones exhibit more fullerene-like cage structures. Cr2Sin− clusters follow the same trend, although with a silicon hexagonal prism structure for n = 14 and 15, and the transition to fullerene-like structures occurring at n = 17. Among these clusters, TM2Si18− have the largest average binding energy and second order differences in energy, therefore the highest relative stability. All of the clusters possess total magnetic moment of 1 μB, but with very different contributions from the doped TM atoms. Especially in the Cr doped clusters there is a tendency towards an anitiferromagnetic arrangement of the magnetic moments of the two Cr atoms.