Nuclear Hyperfine Interactions in Diatomic Molecules and the Ground State of VO

Abstract

THE identification of the ground states of the diatomic oxides of the transition metals presents interesting experimental1 and theoretical2 problems, and the VO molecule is one example. Analogy with TaO suggests3 that the lowest state should be σ2δ 2Δ, but theoretical calculations4 indicate that it is σδ2 4Σ−. This is supported by unpublished observations of P. H. Kasai and W. Weltner of the electron spin resonance spectrum of matrix isolated VO. A rotational analysis5 of several bands of the green system (ν00= 17,419 cm−1) led to values of the internuclear distances in the two states, but the transition was not identified: it was suggested that it might be spin-forbidden.