Quenching of the orbitally-degenerate nickel, palladium, and platinum cations (d9, 2D52) in rare-gas matrices: ESR evidence

The ions, Ni+, Pd+, Pt+ (all having 2D52 ground electronic states) were produced in the plasma formed during laser vaporization of the metals and directly trapped in solid argon and krypton at 4 K. Electron-spin-resonance (ESR) spectra indicated that the ions are in randomly-oriented axially-symmetric crystal fields, leading to partial quenching of their orbital angular momenta such that their g values are in the range of 2 to 3.5. Hyperfine-structure evidence indicates that whereas Pd+ (and then probably Ni+) is in a tetragonally-distorted cubic field, Pt+ is quenched in a pseudotetrahedral site. This unexpected anomaly is discussed.