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

Jacob Baker (1) , Françoise Launay (2)

1 Division of Environmental Health and Risk Management, School of Geography, Earth, and Environmental Sciences, University of Birmingham
2 LERMA - Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique

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 ~94 225 cm^-1 (106.1 nm) has three observable bandheads and is partially overlapped with the strong C ¹Sigma⁺-X ¹Sigma⁺ (1-0) transition at lower energy. It is assigned to the c ³Pi-X ¹Sigma⁺ (1-0) transition. The other band at ~94 437 cm^-1 (105.9 nm) with one clear bandhead is assigned to the k ³Pi-X ¹Sigma⁺ (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 ³Pi valence and c ³Pi 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 ³Pi (v=1) state is identified and discussed.

Domaines: Astrophysique [astro-ph]

Jacob Baker, Françoise Launay. Identification and analysis of the perturbed c 3Pi(v=1)-X 1Sigma+ and k 3Pi(v=5)-X 1Sigma+ absorption bands of carbon monoxide. Journal of Chemical Physics, 2005, 123, pp.4302. ⟨10.1063/1.2136869⟩. ⟨hal-03785490⟩