An accurate ab initio configuration interaction calculation has established that the ground electronic state of B2 is of 3Σ g - symmetry, and that the Douglas-Herzberg emission system near 3200 Å is due to transitions from the second 3Σ u - state to the X 3Σg - state. The lowest 5Σu - state, suggested by previous calculations as the ground state, is found to lie about 1300 cm-1 above the X 3Σg - state. The assignment of the Douglas-Herzberg transition is based on the close agreement between calculated and observed molecular constants which, with observed values in parentheses, are Re,( 3Σg -)=1.622(1.590) Å, ωe(3Σg -)=988.5(1035.2) cm-1, Re(23Σu -)=1.660(1.625)Å, ωe(23Σ u -)=884.5(929.3) cm-1, and Te(2 3Σu -)=31438(30546.1) cm-1. Further support for this assignment is seen in the close agreement between calculated and observed isotope shifts and intensity distributions. An explanation is given for why the 1 3Σu --X 3Σg - transition has not been observed.
|Number of pages||9|
|Journal||Journal of Chemical Physics|
|Publication status||Published - 1978|
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics