Intensity borrowing in high J levels of the c³π-X¹Σ⁺ (0-0) transition of carbon monoxide

Several weak new absorption lines in the room temperature spectrum of carbon monoxide have been identified in the 108.9 - 109.0 nm wavelength range. The lines emerge from the long wavelength side of the C(1)Sigma(+)-X(1)Sigma(+) (0-0) band and appear to form a single rotational branch. Their most probable assignments are to high J lines (J > 40) of the P-O branch of the c(3)Pi-X(1)Sigma(+) (0-0) band rather than to lines of the k(3)Pi-X(1)Sigma(+) (2-0) band. The appearance of these lines may be explained by intensity borrowing from the C-X (0-0) transition as a result of mixing between the f(1e), spin-parity component of the c(3)Pi state and the C(1)Sigma(+) state, which are predicted to cross in this energy region. (c) 2005 Elsevier B.V. All rights reserved.