Observation and modeling of bound-free transitions to the (XS+)-S-1 and a(3)S???????(+) states of KCs

The oscillation continuum in laser-induced fluorescence spectra of bound-free c(3)sigma(+) -> a(3)sigma(+) and (4)(1)sigma(+) -> X-1 sigma(+) transitions of the KCs molecule was recorded by a Fourier-transform spectrometer and modeled under the adiabatic approximation. The required interatomic potentials for ground a(3)sigma(+) and X-1 sigma(+) states were reconstructed in an analytical Chebyshev-polynomial-expansion form in the framework of the regularization direct-potential-fit procedure based on the simultaneous consideration of experimental line positions from Ferber et al. [Phys. Rev. A 80, 062501 (2009)] and the present ab initio calculation of short-range repulsive potential data. It was proved that the repulsive part over the dissociation limit of the derived a(3)sigma(+) potential reproduces the experiment better than the potentials reported in the 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(+) -> X-1 sigma(+) spectrum with equal quality in the range of observations.& nbsp;Published under an exclusive license by AIP Publishing.