Photofragmentation of mass-selected vanadium doped cobalt cluster cations

摘要

The stability of mass-selected vanadium doped cobalt cluster cations (Co n−1V+, n = 11–21 and Co13−m V m +, m = 0–3) is studied by photofragmentation. The clusters are produced by pulsed laser vaporization, mass-separated in a dual reflectron time-of-flight mass spectrometer, and photodissociated using the second harmonic of a Nd:YAG laser. The recorded fragmentation spectra show that all studied clusters prefer dissociation by loss of a cobalt atom. Sequential cobalt atom evaporation is found at higher laser fluences. No dissociation channel involving vanadium loss is observed, consistent with the V-Co bonds being stronger than the Co-Co bonds. Co12V+, which was predicted to have an icosahedral symmetry, is found to be the most stable cluster among the singly vanadium doped species. Consecutive increment of the vanadium concentration along the Co13 − m V m + (m = 0–3) series further confirms the enhanced stability of Co12V+, in excellent agreement with theoretical predictions [S. Datta, M. Kabir, T. Saha-Dasgupta, A. Mookerjee, Phys. Rev. B 80, 085418 (2009)].