Abstract
Large discrepancies in the published photoabsorption oscillator strengths of the vacuum-ultraviolet (VUV) bands of CO hamper the interpretation of VUV astronomical observations. We report new oscillator strength measurements of the (0, 0) and (1, 0) bands of the CO B1Σ+-X1Σ+ electronic system determined from high-resolution (resolving power ≈ 750,000) absorption spectra recorded with a tunable VUV laser system. The instrumental bandwidth (~ 0.14 cm-1 FWHM) was significantly less than the widths of the Doppler-broadened CO lines (~ 0.20 cm-1 FWHM). The B(0)-X(0) and B(1)-X(0) band oscillator strengths, derived from measurements of the photoabsorption cross sections of 36 individual rotational lines, are (6.5 ± 0.6) × 10-3 and (1.1 ± 0.1) × 10-3, respectively. Our results are compared with other recent laboratory measurements and with ab initio calculations.