Electron spin resonance investigation of Sc?+ in neon matrices and assignment of its ground electronic state as X ???. comparison with theoretical calculations

The discandium radical cation, Sc+2 , has been isolated in neon matrices at 4 K and studied by electron spin resonance (ESR) spectroscopy and theoretical methods. It was produced by the x-irradiation of neon matrix samples containing neutral ScZ which was formed by trapping the products generated from the pulsed laser vaporization of scandium metal. The experimental and theoretical findings indicate that Sc2+ has a 4?-g electronic ground state compared to an X5?-u; state for the neutral discandium radical. The large decrease in the 45Sch hyperfine interaction (A tensor) going from ScZ to SC? provides direct experimental information concerning the types of valence molecular orbitals that are involved in these diatomic radicals. The neon matrix magnetic parameters for 45Sc2+ are gll~ 2.00, gl =1.960(l), I+ ]=28(6), and IA, | =26.1(3) MHZ; the D value (zero field splitting) was 15 38 l(3) MHz. Ab initio configuration interaction (CI) calculations of the nuclear hyperfine interactions yielded results in reasonable agreement with the experimental observations.