Fourier-transform spectroscopy of (4)1Σ+ → A 1Σ+ - b 3Π, A 1Σ+ - b 3Π → X1Σ+, and (1)^3Δ _1rArr b{ }^3Π _{0^± } transitions in KCs and deperturbation treatment of A 1Σ+ and b 3Π states
Abstract
High resolution Fourier-transform spectroscopy data of term values in the spin-orbit (SO) coupled first excited A 1Σ+ and b 3Π states in KCs were obtained from (4)1Σ+ → A 1Σ+ - b 3Π, A 1Σ+ - b 3Π → X1Σ+, and (1)^3Δ _1rArr b{ }^3Π _{0^± } spectra of laser-induced fluorescence (LIF). About 3000 new rovibronic term values of the A 1Σ+ and b{ }^3Π _Ω states were obtained with an uncertainty about 0.01 cm-1 and added to the previously obtained 3439 term values in Kruzins et al. [Phys. Rev. A 81, 042509 (2010)] and 30 term values of the b{ }^3Π _{0^+} state levels below the A 1Σ+ state in Tamanis et al. [Phys. Rev. A 82, 032506 (2010)]. The data field was extended considerably, going down to vibrational level vb = 0 and up in energy to 13 814 cm-1, as compared to previously achieved vb = 14 and E = 13 250 cm-1. Overall 6431 e-symmetry term values of 39K133Cs were included in 4 × 4 coupled-channel deperturbation analysis. The analytical Morse-Long-Range (MLR) function yielded empirical diabatic potentials for the A 1Σ+ and b{ }^3Π _{0^+} states while the morphing of the SO ab initio points [J. T. Kim et al., J. Mol. Spectrosc. 256, 57 (2009)] provided the empirical diagonal and off-diagonal SO functions. Overall 98.5% of the fitted term values were reproduced with a rms (root mean square) uncertainty of 0.004 cm-1. The reliability of the model is proved by a good agreement of predicted and measured term values of the 41K133Cs isotopologue, as well as of measured and calculated intensities of (4)1Σ+ → A 1Σ+ - b 3Π LIF progressions. Direct-potential-fit of low-lying vb levels of the b{ }^3Π _{0^-} component yielded the MLR potential which represents the 204 f-symmetry experimental term values with a rms uncertainty of 0.002 cm-1. The Ω-doubling of the b 3Π0 sub-state demonstrates a pronounced vb-dependent increase.
- Publication:
-
Journal of Chemical Physics
- Pub Date:
- December 2013
- DOI:
- 10.1063/1.4844275
- Bibcode:
- 2013JChPh.139x4301K
- Keywords:
-
- excited states;
- fluorescence;
- Fourier transform spectra;
- infrared spectra;
- Morse potential;
- potassium compounds;
- rotational-vibrational states;
- spectral line intensity;
- 33.20.Ea;
- 33.70.Fd;
- 34.20.-b;
- 33.15.Mt;
- 33.50.Dq;
- Infrared spectra;
- Absolute and relative line and band intensities;
- Interatomic and intermolecular potentials and forces potential energy surfaces for collisions;
- Rotation vibration and vibration-rotation constants;
- Fluorescence and phosphorescence spectra