The comet-tail (A(2)Pi(i)-X-2 Sigma(+)) system of (CO+)-C-12-O-16: A reinvestigation

The emission spectrum of the comet-tail (A2 Pi(i)-X(2)Sigma(+)) system of ( CO+)-C-12-O-16 produced in the cathode glow of a hollow-cathode discharge t ube and photographed in the spectral region 3345-8500 Angstrom at high reso lution was reinvestigated. Detailed rotational analysis of 10 bands involvi ng 5 vibrational levels v = 0 to 4 of each of the A and X states was carrie d out. Spin-splitting of the rotational levels was observed for the analyze d bands. The observed intensity distribution of the branches is found to be in good agreement with theoretical calculations. Molecular constants for b oth the A and X states were obtained from a global fit of the present data of the A-X system and the infrared and microwave data available from the li terature for v = 0, 1, 2, 3, and 4 of state X, using effective Hamiltonian for the A(2)Pi state and matrix elements for both A and X states. The prese nt work suggests that the A(2)Pi(i) state changes from Hund's case (a) at l ow J values to Hund's case (b) at high J values. (C) 2000 Academic Press.