Observation of D(2)1Π∼(2)3Π∼(2)3Σ+ states in KCs by polarisation labelling spectroscopy technique. Modelling of the D(2)1Π ∼ (2)3Π1 system

• Published in: Journal of quantitative spectroscopy & radiative transfer Vol. 248
• Main Authors: Szczepkowski, Jacek, Grochola, Anna, Kowalczyk, Pawel, Jastrzebski, Wlodzimierz
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-06-2020
• Subjects: Alkali dimers; Coupled channels model; Dunham coefficients; Electronic states; KCs; Laser spectroscopy; Electronic states; Alkali dimers; Laser spectroscopy; KCs; Coupled channels model; Dunham coefficients
• ISSN: 0022-4073; 1879-1352
• DOI: 10.1016/j.jqsrt.2020.106984

•The 21Π∼23Π∼33Σ+←X1Σ+ band systems of KCs molecule observed by polarisation labelling spectroscopy.•More than 6000 observed rovibrational levels of the 21Π∼23Π∼33Σ+ system.•Analytical coupled channels model of the 21Π ~23Π1 system.•Set of Dunham and coupling coefficients for interacting 21Π and 23Π1 states reproduces energies of over 2000 rovibrational levels with rms error below 0.03cm−1.
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A first attempt towards analysis of three strongly interacting electronic states in KCs molecule, D(2)1Π, (2)3Π, and (2)3Σ+, is presented. In this attempt a two-channel model is built for the D(2)1Π ∼ (2)3Π1 system. Our description results in two sets of Dunham-type coefficients and effective coupling terms, which allow to reproduce 2008 experimental values of energy levels for both states with an accuracy 0.029 cm−1 in the range of vibrational levels below v=13 where no influence from the (2)3Σ+ state is observed.