HIGH-RESOLUTION OSCILLATOR STRENGTH MEASUREMENTS OF THE ν'=0,1 BANDS OF THE B-X, C-X, AND E-X SYSTEMS IN FIVE ISOTOPOLOGUES OF CARBON MONOXIDE

We report oscillator strengths for six strong vibrational bands between 105.0 and 115.2 nm, associated with transitions from the upsilon = 0 level of the X (1)Sigma(+) ground state to the upsilon = 0 and 1 levels of the B (1)Sigma(+), C (1)Sigma(+), and E (1)Pi. states, in (CO)-C-12-O-16, (CO)-C-12-O-17, (CO)-C-12-O-18, (CO)-C-13-O-16, and (CO)-C-13-O-18. These measurements extend the development of a comprehensive database of line positions, oscillator strengths, and linewidths of photodissociating transitions for all astrophysically relevant CO isotopologues. The E- X bands, in particular, play central roles in CO photodissociation and fractionation models of interstellar clouds and circumstellar disks including the early solar nebula. The resolving powers of the room- temperature measurements, R = 300,000-400,000, allow for the analysis of individual line strengths within bands; the measurements reveal J-dependences in the branch intensities of the C(upsilon = 0,1)- X(0) and E(upsilon = 0,1)- X(0) bands in all isotopologues. Minimal or no isotopologue dependence was found in the f- values of the C(upsilon = 0,1)- X(0) and E(upsilon = 0,1)-X(0) bands at a similar to 5% uncertainty level. Revised dissociation branching ratios for the C(upsilon = 0,1) and E(upsilon = 0,1) levels are computed based on these f- values. The weak isotopologue dependence of the f- values presented here eliminates this mechanism as an explanation for the large O-17 enrichments seen in recent laboratory photolysis experiments on CO at wavelengths from 105 to 108 nm.