Experimental Studies of the NaCs 53Π0 and 1(a)3Σ+ States

We present experimental studies of the NaCs molecule that are currently underway in our laboratory. The opticaloptical double resonance method is used to obtain Doppler-free excitation spectra for several excited states. Selected data from the 53Π0 electronic state are used to obtain Rydberg-Klein-Rees (RKR) and Inverse Perturbation Approach (IPA) potential curves. We are also mapping the repulsive wall of the 1(a) 3Σ +potential using many resolved bound-free fluorescence spectra from individual ro-vibrational levels of the 53Π0 electronic state to the 1(a) 3Σ + state. Using the determined 53Π0 state potential we fit the repulsive wall of the 1(a) 3Σ + state to reproduce the experimental spectra using LeRoy’s BCONT program. A slightly modified version of BCONT is also used to fit the relative transition dipole moments, µe(R), as a function of internuclear separation R, for the various bound-free electronic transitions

Experimental Studies of the NaCs 53Π0 and 1(a)3Σ+ States

We present experimental studies of the NaCs molecule that are currently underway in our laboratory. The opticaloptical double resonance method is used to obtain Doppler-free excitation spectra for several excited states. Selected data from the 53Π0 electronic state are used to obtain Rydberg-Klein-Rees (RKR) and Inverse Perturbation Approach (IPA) potential curves. We are also mapping the repulsive wall of the 1(a) 3Σ +potential using many resolved bound-free fluorescence spectra from individual ro-vibrational levels of the 53Π0 electronic state to the 1(a) 3Σ + state. Using the determined 53Π0 state potential we fit the repulsive wall of the 1(a) 3Σ + state to reproduce the experimental spectra using LeRoy’s BCONT program. A slightly modified version of BCONT is also used to fit the relative transition dipole moments, µe(R), as a function of internuclear separation R, for the various bound-free electronic transitions

Experimental and theoretical studies of the coupled A 1 Σ + and b Π 3 states of NaK

International audienceWe report an extensive series of transitions (including collisional transfer lines) from pure and mixed levels of the NaK A1Σ+ and b3Π states to the X1Σ+ state, observed at the Université Lyon 1 using Fourier-transform spectroscopy. We then combine these data with previously reported data on these states from emission from the B1Π and C1Σ+ states and from mutually perturbed levels of the D1Π and d3Π states. We obtain 2758 distinct term values: the full data set includes 11 624 term values, with many multiple determinations from transitions over a range of vibrational and rotational levels. The data are analyzed by fitting to potentials of the “Hannover” form [C. Samuelis et al., Phys. Rev. A 63, 012710 (2000)] plus spin-orbit (SO) functions in a simple Morse form, yielding an rms residual of approximately 0.029 cm−1. The empirical SO functions agree well with their ab initio counterparts obtained from electronic structure calculations based on nonempirical effective core potentials. From level energies of the A−b complex calculated from the fitted potentials and SO functions, we identify reasonable candidates for transitions between Feshbach resonance states and mixed singlet-triplet gateway levels of the A1Σ+−b3Π manifold, leading either to v=0 levels of the X state or to mixed singlet-triplet levels at higher energies that can be used for perturbation-facilitated double-resonance experiments

The 39K2 2 3Σg+ state: Observation and analysis

International audienceThe 39K2 2 3Σg+ state has been observed by perturbation-facilitated infrared-infrared double resonance spectroscopy and two-photon excitation. Resolved fluorescence spectra into the a 3Σu+ state have been recorded. The observed vibrational levels have been assigned as the v=23-25, 27, 28, 31-33, 38-45, 47, and 53 levels by comparing the observed and calculated spectra of the 2 3Σg+-->a 3Σu+ transitions. Molecular constants have been obtained using a global fitting procedure with a comprehensive set of experimental data. Fine and hyperfine splittings have been resolved in the excitation spectra. Perturbations between the 2 3Σg+ and 2 3Πg states were observed. The hyperfine patterns of the 2 3Σg+ levels are strongly affected by the perturbation. The perturbation-free and weakly perturbed levels follow the case bβS coupling scheme, while the perturbed levels follow case bβJ coupling. A Fermi contact constant, bF=65+/-10 MHz, has been obtained. Intensity anomalies of rotational lines appeared both in the 2 3Σg+~2 3Πga 3Σu+ resolved fluorescence spectra. These intensity anomalies can be explained in terms of a quantum-mechanical interference effect