PREDISSOCIATION RATES IN CARBON-MONOXIDE - DEPENDENCE ON ROTATIONAL STATE, PARITY AND ISOTOPE

A high-resolution spectroscopic study Of carbon monoxide has been performed using a narrow-band and tunable extreme-ultraviolet Iaser source in the wavelength range 91-97 nm. For three isotopes (CO)-C-12-O-16, (CO)-C-13-O-16 and (CO)-C-13-O-18 the (4ppi)L 1pi, upsilon = 0, (4psigma)K 1SIGMA+, upsilon = 0 and (3ssigma)W 1PI, upsilon = 0 states were investigated. The 1PI, upsilon = 2, (3ssigma)W 1PI, upsilon = 2 and (3dpi)L' 1PI, upsilon = 1 states were studied for (CO)-C-12-O-16 and (CO)-C-13-O-16. The 1PI, upsilon = 0 state at 109564.58 cm-1, the (6psigma) 1SIGMA+, upsilon = 0 state at 109173.68 cm-1, the (5psigma) 1SIGMA+, upsilon = 0 state at 107174.44 cm-1, and the (4dsigma) 1SIGMA+, upsilon = 0 state at 105676.30 cm-1 were excited only for the main isotope (CO)-C-12-O-16. Previously unknown states are found at 107365.87 cm-1 (1SIGMA+) for (CO)-C-12-O-16 and at 103203.07 cm-1 (1PI) for (CO)-C-13-O-18. Indirect evidence is found for a perturber state at 107708 +/- 2 cm-1 for (CO)-C-12-O-16, while spectroscopic information on the E 1PI, upsilon = 5 state of (CO)-C-13-O-18 is deduced from a deperturbation analysis. A rotational-state and isotope-dependent predissociation rate is found for almost all states. A parity dependence is observed for the (4ppi)L 1PI, upsilon = 0 and (3ssigma)W 1PI, upsilon = 0 states, where the predissociation mte of the PI(e) component varies proportional to J(J + 1). This effect is attributed to a coupling with the repulsive part of the D' 1SIGMA+ state. Several examples of accidental predissociations have been found, particularly in the (4dsigma) 1SIGMA+, upsilon = 0 state.