FOURIER-TRANSFORM EMISSION-SPECTROSCOPY OF TAO

The emission spectrum of TaO, excited in a tantalum hollow cathode lam p, has been observed at high resolution using a Fourier transform spec trometer. In addition to previously known transitions, a number of new bands have been identified and assigned as belonging to two new elect ronic transitions: H(2)Pi(1/2)-X(2)Delta(3/2) and K(2)Phi(5/2)-X(2)Del ta(3/2). A rotational analysis of the 0-0 and 0-1 bands of the H(2)Pi( 1/2)-X(2)Delta(3/2) transition and of the 0-1, 1-2, 0-0, 1-0, and 2-1 bands of the K(2)Phi(5/2)-X(2)Delta(3/2) transition has been carried o ut, providing the following equilibrium constants for the ground X(2)D elta(3/2) state: omega(e) = 1028.9060(15) cm(-1), omega(e)x(e) = 3.589 28(66) cm(-1), B-e = 0.40289737(139) cm(-1), alpha(e) = 0.00185445(83) cm(-1), and r(e) = 1.6873430(29) Angstrom. The principal molecular co nstants for the H(2)Pi(1/2) state are T-00 = 20 634.32758 (40) cm(-1), B-0 = 0.3766867(31) cm(-1), and r(0) = 1.7450604(72) Angstrom, while the equilibrium constants for the K(2)Phi(5/2) state are omega(e) = 90 5.4549(15) cm(-1), omega(e)x(e) = 3.67601(64) cm(-1), B-e = 0.37965102 (36) cm(-1), alpha(e) = 0.00189370(21) cm(-1), and r(e) = 1.7382343(8) Angstrom. Although the H(2)Pi(1/2) and K(2)Phi(5/2) states have been observed previously in matrix isolation experiments, our work on these states is the first in the gas phase. (C) 1998 Academic Press.