RESUMO
We observe photoabsorption of the W(1) â X(0) band in five carbon monoxide isotopologues with a vacuum-ultraviolet Fourier-transform spectrometer and a synchrotron radiation source. We deduce transition energies, integrated cross sections, and natural linewidths of the observed rotational transitions and find a perturbation affecting these. Following a deperturbation analysis of all five isotopologues, the perturbing state is assigned to the v = 0 level of a previously unobserved (1)Π state predicted by ab initio calculations to occur with the correct symmetry and equilibrium internuclear distance. We label this new state Eâ³ (1)Π. Both of the interacting levels W(1) and Eâ³(0) are predissociated, leading to dramatic interference effects in their corresponding linewidths.
RESUMO
The forbidden c(3)Pi-X(1)Sigma(+) (0-0) absorption band of carbon monoxide has been reinvestigated under different pressure conditions using the 10.7-m VUV spectrograph at Meudon. Overlap with the allowed C(1)Pi-X(1)Sigma(+) (0-0) band at lower transition energy has been taken into account. We have identified a new rotational branch corresponding to an S-type branch and extended the analysis to both higher and lower J. An analysis of the band structure and the low J transition lines suggests that the band gains its intensity predominantly as a result of an interaction of the c(3)Pi state with a (1)Sigma(+) state, most likely the C(1)Sigma(+) (v = 0) state. Molecular constants have been obtained for the c(3)Pi state that are in reasonable agreement with those previously published. The apparently anomalous small value for the centrifugal distortion constant is explained by a homogeneous perturbation with the k(3)Pi valence state. Copyright 2000 Academic Press.
