Fourier transform spectroscopy and direct potential fit of a shelflike state: Application to E(4)(1)Sigma(+) KCsстатья
Статья опубликована в высокорейтинговом журнале
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Дата последнего поиска статьи во внешних источниках: 18 июля 2013 г.
Аннотация:The paper presents high-resolution experimental study and a direct
potential construction of a shelflike state E(4)(1)Sigma(+) of the KCs
molecule converging to K(4(2)S) + Cs(5(2)D) atomic limit; such data are
of interest for selecting optical paths for producing and monitoring
cold polar diatomics. The collisionally enhanced laser induced
fluorescence (LIF) spectra corresponding to both spin-allowed
E(4)(1)Sigma(+) -> X(1)(1)Sigma(+) and spin-forbidden E(4)(1)Sigma(+) ->
a(1)(3)Sigma(+) transitions of KCs were recorded in visible region by
Fourier transform spectrometer with resolution of 0.03 cm(-1). Overall
about 1650 rovibronic term values of the E(4)(1)Sigma(+) state of
(KCs)-K-39-Cs-133 and (KCs)-K-41-Cs-133 isotopologues nonuniformly
covering the energy range {[}16987, 18445] cm(-1) above the minimum of
the ground X-state were determined with the uncertainty of 0.01 cm(-1).
Experimental data field is limited by vibrational levels v' is an
element of {[}2, 74] with rotational quantum numbers J' is an element of
{[}1, 188]. The closed analytical form for potential energy curve (PEC)
based on Chebyshev polynomial expansion (CPE) was implemented to a
direct potential fit (DPF) of the experimental term values of the most
abundant (KCs)-K-39-Cs-133 isotopologue. Besides analyticity,
regularity, correct long-range behavior, and nice convergence
properties, the CPE form demonstrated optimal balance on flexibility and
constraint for the DPF of a shelflike state aggravated by a limited data
set. The mass-invariant properties of the CPE PEC were tested by the
prediction of rovibronic term values of the (KCs)-K-41-Cs-133 isotopomer
which coincided with their experimental counterparts with standard
deviation of 0.0048 cm(-1). The CPE modeling is compared with the highly
flexible pointwise inverted perturbation approach model, as well as with
conventional Dunham analysis of restricted data set v' <= 50.
Reliability of the empirical PEC is additionally confirmed by good
agreement between the calculated and experimental relative intensity
distributions in the long E(v') -> X(v `') LIF progressions.