Infrared Emission Spectroscopy of the A′3σ+ -A3π Band of CS

The infrared emission spectrum of the CS a'(3)Sigma(+ )- a(3)Pi transition has been observed with a FT spectrometer in the 1800-10,500 cm(-1) region. Thirteen bands were analyzed to obtain molecular constants in 4 (v = 0-3) vibrational states of a(3)Pi and 7 (v = 0-6) vibrational states of a'(3)Sigma(+ ) where the effects of perturbations from nearby states were taken into account directly by using an energy matrix that includes off-diagonal spin-orbit and rotational interactions. Due to the large spin-orbit interaction, inclusion of higher-order terms of the perturbation was necessary for the fitting. The vibrational energies of v = 0-5 in a'(3)Sigma(+ )have been determined experimentally for the first time, and a simultaneous analysis with the previous data of v = 7-22 gives T-e0 = 30689.40(40), omega(e) = 830.680(87), omega(e)x(e) = 5.0372(38) cm(-1) for a'(3)Sigma(+ ), with one standard deviation in parentheses. (C) 2019 Elsevier Inc. All rights reserved.