Electronic and geometric structures of vanadium cluster ions; V-n(+) (n=3-5), studied by optical absorption spectroscopy

Optical absorption spectra of vanadium cluster ions, V-n(+) (n=3-5) were ob tained in the IR-UV region by measuring photodissociation action spectra of their argon-atom complexes. The spectra were analyzed with the aid of the density functional theory to obtain their most probable geometric and elect ronic structures. V-3(+) was shown to be an isosceles triangular structure with bond lengths of 2.5 Angstrom and the apex angle of 42 degrees. On the other hand,V-5(+) was found to have a trigonal bipyramid structure with an isosceles basal triangle (two bond lengths of 2.6 Angstrom and the other of 2.2 Angstrom) and a pair of three legs (two of 2.4 Angstrom and the other of 2.2 Angstrom). Analysis of the spin configuration indicates that V-3(+) and V-5(+) exhibit high-spin characters (triplet), where the spin magnetic moments at each atomic site couples in an anti-parallel manner. They are in contrast to V-4(+), which has been shown in our previous study to be in th e lowest spin state. (C) 2000 Elsevier Science B.V. All rights reserved.