Identification and analysis of the perturbed c (3)Pi(v=1)-X-1 Sigma(+) and k(3)Pi(v=5)-X-1 Sigma(+) absorption bands of carbon monoxide

Two new red-degraded bands in the room-temperature vacuum-ultraviolet absorption spectrum of carbon monoxide have been identified in the 94 000-94 500 cm(-1) energy region and analyzed. One of the bands at approximate to 94 225 cm(-1) (106.1 nm) has three observable bandheads and is partially overlapped with the strong C (1)Sigma(+)-X (1)Sigma(+) (1-0) transition at lower energy. It is assigned to the c (3)Pi-X (1)Sigma(+) (1-0) transition. The other band at approximate to 94 437 cm(-1) (105.9 nm) with one clear bandhead is assigned to the k (3)Pi-X (1)Sigma(+) (5-0) transition. A strong homogeneous perturbation was found to exist between the two upper states that strongly influences the line positions and shapes of these bands. A rotational deperturbation analysis was performed and molecular rotational constants for both upper states were determined. These deperturbed molecular constants are entirely consistent with the expected values for the k (3)Pi valence and c (3)Pi Rydberg states. The Hamiltonian interaction term between these two states is found to be separable into vibrational and electronic factors and the electronic factor is determined to be H-e=323 +/- 40 cm(-1). A discrepancy in the literature regarding the location of the c (3)Pi (v=1) state is identified and discussed. (c) 2005 American Institute of Physics.