Spectra in the vacuum ultraviolet region of CO in gaseous and solid phases and dispersed in solid argon at 10 K

With radiation in the region 104-170 nm from a synchrotron and dispersed with a grating monochromator at spectral resolution 0.02-0.03 nm, we measured absorption spectra of (CO)-C-12-O-16 in the gaseous phase at 303 K and in the solid phase at 10 K, and dispersed in solid argon at molar ratios Ar:CO = 10, 50 and 250 and at 10 K. We assign observed spectral features to transitions to electronic states A (1)Pi, B (1)Sigma(+), C (1)Sigma(+) and E (1)Pi from the ground state X (1)Sigma(+). Vibrational progressions are discernible for all these systems of CO in the gaseous phase, but for only the system A-X for CO in the pure solid phase of CO or a dispersion in solid argon; for all condensed phases, multiple series of features are deducible in this vibrational structure.