LIFETIME MEASUREMENTS OF THE E(1)PI, UPSILON=0 AND UPSILON=1 STATES OF (CO)-C-12-O-16, (CO)-C-13-O-16, AND (CO)-C-13-O-18

In a laboratory investigation using tunable picosecond lasers in a pum p-probe configuration, lifetimes of the E (II)-I-1, v = O and v = 1 st ates of CO are experimentally determined. For E (II)-I-1, v = 1, the l ifetime is found to vary significantly for the isotopomers. Combining the data with existing oscillator strengths, predissociation probabili ties within the range of 93.6%-98.64% result for (CO)-C-12-O-16, (CO)- C-13-O-16, and (CO)-C-13-O-18 in, the case of the E (II)-I-1, v=1 stat e, which is the state that predominantly influences the isotopic fract ionation of CO in interstellar clouds.