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[en] In this note, three vibrational bands of the electronic transition A"2Σ"+-X"2Π of the N_2O"+ radical (000-100, 100-100, and 001-101) were theoretically analysed. Starting from Hamiltonian models proposed for this kind of molecule, their parameters were calculated using a Levenberg-Marquardt fit procedure in order to reduce the root mean square deviation from the experimental transitions below to 0.01 cm"−"1. The main objective of this work is to obtain new and reliable values for rotational constant B″ and the spin-orbit interaction parameter A of the analysed vibrational levels of the X"2Π electronic state of this molecule

[en] In this article three vibrational bands of the electronic transition A²Σ⁺-X²Π of the N₂O⁺ radical (100-000, 000-001, and 001-001) are analysed through high resolution Fourier transform spectroscopy. The N₂O⁺ radical was produced by Penning ionization of N₂O by colliding with metastable atoms of He(2³S) in a reaction chamber. The spectra was recorded in a spectral range of 24 500–30 000 cm⁻¹ and obtained from 200 coadded interferograms recorded at an apodized resolution of 0.08 cm⁻¹. Through a recursive way, the wavenumbers of the correspondent rotational transitions were reduced into molecular constants, improving the values previously reported. New values for the first vibrational energies ν₁^′, ν₃^″, and ν₃^′ are also obtained and compared with previous values reported in the literature

[en] We propose a two-step genetic algorithm (GA) to fit potential energy curves to both ab initio and spectroscopic data. In the first step, the GA is applied to fit only the ab initio points; the parameters of the potential so obtained are then used in the second-step GA optimization, where both ab initio and spectroscopic data are included in the fitting procedure. We have tested this methodology for the extended-Rydberg function, but it can be applied to other functions providing they are sufficiently flexible to fit the data. The results for NaLi and Ar₂ diatomic molecules show that the present method provides an efficient way to obtain diatomic potentials with spectroscopic accuracy

[en] The current interest in producing ultracold RbCs molecules by optical excitation from weakly bound Feshbach resonances and stimulated decay to the absolute ground state requires detailed analyses of the intermediate excited states. In this study, we present two sets of experimental Fourier-transform spectroscopic data of the A ¹Σ⁺-b ³Π complex. The A-b mixed vibrational levels are the most likely candidates to be intermediates in the molecular formation. The more recent and more accurate data set is from mixed A-b→X transitions, while the second is derived in large part from (4) ¹Σ⁺→A-b emission and extends to higher A-b energy levels. From a detailed analysis of the spectroscopic data we obtain term values which allow one to construct potentials and spin-orbit functions. Vibrational numbering of the A state has been raised by one quantum over a previous report [T. Bergeman et al., Phys. Rev. A 67, 050501 (2003)] while the numbering of the b state is established with a considerable degree of certainty with help of data on the ⁸⁵Rb¹³³Cs and ⁸⁷Rb¹³³Cs isotopomers. In addition, we have performed calculations of spin-orbit functions by two distinct methods. The fitted spin-orbit coupling matrix element between the two Ω^p=0⁺ states, A ¹Σ⁺ and b ³Π₀₊, happens to agree rather well with the results from both of these methods, while for the diagonal b ³Π state spin-orbit function, the fitted function agrees fairly well with that obtained by the other method.