Fourier-transform spectroscopy and potential construction of the (2)1Π state in KCs

The paper presents an empirical pointwise potential energy curve (PEC) of the (2)(1)Pi state of the KCs molecule constructed by applying the Inverted Perturbation Approach routine. The experimental term values in the energy range E(v', J') is an element of [15 407; 16 579] cm(-1) involved in the fit were based on Fourier-Transform spectroscopy data obtained with 0.01 cm(-1) accuracy from the laser-induced (2)(1)Pi -> X-1 Sigma(+) fluorescence spectra. Buffer gas Ar was used to facilitate the appearance of rotation relaxation lines in the spectra, thus enlarging the (2)(1)Pi data set and allowing determination of the Lambda-splitting constants. The data set included vibrational v' is an element of [0,28] and rotational J' is an element of [7,274] quantum numbers covering about 67% of the potential well. The present PEC reproduces the overall set of data included in the fit with a standard deviation of 0.5 cm(-1). The obtained value of the Lambda-doubling constant q = +1.8 x 10(-6) cm(-1) for J' > 50 and v' is an element of [0,6] is in an excellent agreement with q = +1.84 x 10(-6) cm(-1) reported in Kim, Lee, and Stolyarov [J. Mol. Spectrosc. 256, 57-67 (2009)]. (C) 2015 AIP Publishing LLC.