Perturbation study via rotational-resolved spectrum in the triplet band d³Δ-a³\Pi(2, 1) of CO

The triplet band d³Δ-a³\Pi (2, 1) of the CO molecule in the near infrared region of 12350--12850cm^-1 has been observed and analysed by taking into account the perturbation interaction between the d³Δ(v = 2) and a³\Pi (v = 9) states. The most perturbed lines and most precise perturbation parameters, \alpha_2 and \beta_2, and electronic perturbation constants, \xi_\rm e and \eta_\rm e , for the d³Δ (v= 2) and ³\Pi (v = 9) states have been obtained.