Observation and modelling of bound-free transitions to the $X^1\Sigma^+$ and $a^3\Sigma^+$ states of KCs

• Main Authors: Krumins, Valts, Kruzins, Artis, Tamanis, Maris, Ferber, Ruvin, Meshkov, Vladimir V, Pazyuk, Elena A, Stolyarov, Andrey V, Pashov, Asen
• Format: Journal Article
• Language: English
• Published: 28.01.2022
• Subjects: Physics - Atomic Physics; Physics - Chemical Physics
• DOI: 10.48550/arxiv.2201.11956

The oscillation continuum in laser-induced fluorescence spectra of bound-free $c^3\Sigma^+ \to a^3\Sigma^+$ and (4)$^1\Sigma^+ \to X^1\Sigma^+$ transitions of the KCs molecule were recorded by Fourier-transform spectrometer and modelled under the adiabatic approximation. The required interatomic potentials for ground $a^3\Sigma^+$ and $X^1\Sigma^+$ states were reconstructed in an analytical Chebishev-polynomial-expansion form in the framework of the regularization direct-potential-fit procedure based on the simultaneous consideration of experimental line positions from [R. Ferber et al, Phys. Rev. A, \textbf{80}, 062501 (2009)] and the present \emph{ab initio} calculation of short-range repulsive potential data. It was proved that the repulsive part over dissociation limit of the derived $a^3\Sigma^+$ potential reproduces the experiment better than the potentials reported in literature. It is also shown that all empirical and semi-empirical potentials available for the $X^1\Sigma^+$ state reproduce the bound-free (4)$^1\Sigma^+ \to X^1\Sigma^+$ spectrum with equal quality in the range of observations.