OPTICAL-OPTICAL DOUBLE-RESONANCE SPECTROSCOPY OF THE A-X AND B-X SYSTEMS OF NA-3

The X and A states of the sodium trimer may be treated as rigid asymme tric rotors of C-2v symmetry. The B state, however, is a floppy molecu le where the three sodium nuclei can perform a pseudorotational motion in the molecular plane. A recently developed model Hamiltonian for th e B state is applied to new rotationally resolved optical-optical doub le resonance measurements of the B-X system of Na,. These recorded tra nsitions, in the u = 1, j = 0, 1, 2, and 3 bands of that system, are f it to the new Hamiltonian and rotational assignments are made. The dou ble resonance technique utilized one dye laser fixed to a transition i n the A-X system while another dye laser was scanned throughout severa l vibronic bands in the B-X system. In addition to providing a substan tially improved signal-to-noise ratio, this method allows for a check of the consistency between previous analyses of both optical systems. (C) 1997 Academic Press.