Perturbation of the a3Π (v =9) and d3Δ (v =2) states of CO

Abstract: One hundred and ninety-nine spectral lines in the (9,1) overtone band of the a3Π state of the CO molecule in the near infrared region of 12,350–12,850cm−1 are observed by employing optical heterodyne and magnetic rotation enhanced concentration modulation spectroscopy for the first time due to the strong perturbation between the v =9 of a3Π and v =2 of d3Δ levels. Additionally, 680 lines in the (2,1) band of CO a3Π–d3Δ system are observed. Therefore, the most accurate molecular constants of these two perturbed levels, together with their perturbation constants, are obtained by non-linear least squares fitting using effective Hamiltonians. Our results show the improvement of about one order. [Copyright &y& Elsevier]