Vacuum Ultraviolet Photodissociation Branching Ratios of 12C16O, 13C16O, and 12C18O from 100500 to 102320 cm-1

The ion photofragment spectra and photodissociation branching ratios into the two energetically available channels, C(D-1) + O(P-3) and C(P-3) + O(P-3), have been obtained for the three CO isotopologues, (CO)-C-12-O-16 , (CO)-C-13-O-16, and (CO)-C-12-O-18, in the vacuum ultraviolet range 100500-102320 cm(-1). The two vibronic states of (1)Sigma(+) symmetry, F(3d sigma) (1)Sigma(+)(nu' = 1) and J(4s sigma) (1)Sigma(+)(nu' = 0), predominantly dissociate into the lowest channel C(P-3) + O(P-3) through interactions with the repulsive D'(1)Sigma(+) state. All three vibronic states of (1)Pi symmetry, E'(1)Pi(nu' = 1, 2) and G(3d pi) (1)Pi(nu' = 0), dissociate into both of the channels above. The photodissociation branching ratios into the channel C(D-1) + O(P-3) for E'(1)Pi(nu' = 1, 2) are found to be independent of both the rotational quantum number and elf parity, while those for G(3d pi) (1)Pi(nu' = 0) strongly depend on the rotational quantum number, indicating very different predissociation pathways between the valence states E'(1)Pi(nu' = 1, 2) and the Rydberg state G(3d pi) (1)Pi(nu' = 0). The potential energy curves of CO in the aforementioned energy range and below have recently been well constructed due to a series of interplays between high-resolution spectroscopic studies and theoretical calculations; the photodissociation branching ratios measured in this study can provide further benchmarks for future theoretical investigations which aim to understand the detailed predissociation dynamics of CO.