NARROW-BANDWIDTH VUV LASER MEASUREMENTS OF FINE-STRUCTURE PREDISSOCIATION LINEWIDTHS IN THE SCHUMANN-RUNGE BANDS OF O-2

Fine-structure predissociation linewidths have been measured for the S chumann-Runge bands of O-2 (B-3 Sigma(u)(-) <-- X(3) Sigma(g)(-)). Usi ng two excimer-pumped dye lasers, radiation was generated in the 1800 Angstrom region by four-wave mixing in Xe, achieving a bandwidth of si milar to 0.10 cm(-1) full-width at half-maximum, and resolving lines t o the Doppler limit. The predissociation linewidths are found to vary significantly with vibration, rotation and fine-structure. A predissoc iation model which includes spin-orbit interactions between the B-3 Si gma(u)(-) state and the repulsive 1 (1) Pi(u), 2 (3) Sigma(u)(+) and 1 (5) Pi(u) states, and spin-orbit and L-uncoupling interactions with t he repulsive 1 (3) Pi(u) state, provides a good description of the mea surements.