B Atoms, Diatomic Boron and Dihydro-Boron-Oxide Radical Molecules: ESR and Optical Spectra at 4 Degrees K.

摘要

Elemental boron has been vaporized and trapped in solid argon at 4-10 K. The Douglas-Herzberg transition of B2 has been observed in absorption at 3300 A at 10 K, indicating that the lower Sigma state is the ground electronic state. However, B2 was not observed via ESR, which is interpreted as support for a 3 Sigma(-) sub g ground state with a zero-field splitting greater than about 4/cm, rather than 5 Sigma(-) sub u favored by ab initio calculations. The ESR spectrum of B atoms in solid argon is also detected. It exhibits axial symmetry and almost complete quenching of the orbital angular momentum of the 2P(1/2) free atom, with g(parallel) = 2.0014(5), g(perpendicular) = 1.9645(30). The simple crystal field model has been applied in the interpretation of the g and hyperfine tensors and comparison made with A1 and Ga in argon, as studied by Ammeter and Schlosnagle. The ESR spectrum of H2BO, appearing as an impurity, was observed for the first time, and its magnetic parameters determined. (Author)