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Register a new userObservation and Analysis of Resonant Coupling Between Near-Degenerate Levels of the 2 1Sigma g+ and 1 1 Pi g States of Ultracold 85Rb2
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We report on the anomalously high line strength of a single rotational level in the ultracold photoassociation of two 85Rb atoms to form 85Rb2. The v = 111, J = 5 level belongs to the Hunds case (c) 2 (0g+) state, which correlates to the Hunds case (a) 2 1 Sigma g+ state. Its strength is caused by coupling with a very near-resonant long-range state. The long-range component is the energetically degenerate v = 155, J = 5 level of the case (c) 2 (1g)$ state, correlating to the case (a) 1 1 Pi g state. The line strength is enhanced by an order of magnitude through this coupling, relative to nearby vibrational levels and even to nearby rotational levels of the same vibrational level. This enhancement is in addition to the enhancement seen in all J = 3 and 5 levels of the 2 (0g+) state due to an l = 4 shape resonance in the a 3 Sigma u+ state continuum, which alters the distribution of levels formed by photoassociation.
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We report the first observation of photoassociation to the 2(1)Sigma(g)(+) state of 85Rb2 . We have observed two vibrational levels (v=98, 99) below the 5s1/2+5p1/2 atomic limit and eleven vibrational levels (v=102-112) above it. The photoassociation---and subsequent spontaneous emission---occur predominantly between 15 and 20 Bohr in a region of internuclear distance best described as a transition between Hunds case (a) and Hunds case (c) coupling. The presence of a g-wave shape resonance in the collision of two ground-state atoms affects the photoassociation rate and lineshape of the J= 3 and 5 rotational levels.
We observe a hyperfine anomaly in the measurement of the hyperfine splitting of the 6S_{1/2} excited level in rubidium. We perform two step spectroscopy using the 5S_{1/2}->5P_{1/2}->6S_{1/2} excitation sequence. We measure the splitting of the 6S1/2 level and obtain for the magnetic dipole constants of ^{85}Rb and ^{87}Rb A = 239.18(4) MHz and A=807.66(8) MHz, respectively. The hyperfine anomaly difference of_{87}delta_{85}=-0.0036(2) comes from the Bohr Weisskopf effect: a correction to the point interaction between the finite nuclear magnetization and the electrons, and agrees with that obtained in the 5S_{1/2} ground state.
We combined high-resolution Fourier-transform spectroscopy and large-scale electronic structure calculation to study energy and radiative properties of the high-lying (3)1{Pi} and (5)1{Sigma}+ states of the RbCs molecule. The laser-induced (5)1{Sigma}+(4)1{Sigma}+(3)1{Pi}-A(2)1{Sigma}+ b(1)3{Pi} fluorescence (LIF) spectra were recorded by the Bruker IFS-125(HR) spectrometer in the frequency range { u} 5500 to 10000cm-1 with the instrumental resolution of 0.03 cm-1. The rotational assignment of the observed LIF progressions, which exhibit irregular vibrational-rotational spacing due to strong spin-orbit interaction between A1{Sigma}+ and b3(Pi) states was based on the coincidences between observed and calculated energy differences. The required rovibronic term values of the strongly perturbed A-b complex have been calculated by a coupled-channels approach for both 85Rb133Cs and 87Rb133Cs isotopologs with accuracy of about 0.01 cm-1, as demonstrated in A. Kruzins et al. [J. Chem. Phys. 141, 184309 (2014)]. The experimental energies of the upper (3)1(Pi) and (5)1{Sigma}+ states were involved in a direct-potential-fit analysis performed in the framework of inverted perturbation approach. Quasirelativistic ab initio calculations of the spin-allowed (3)1{Pi},(5)1{Sigma}+- (1-4)1{Sigma}+(1-3)1{Pi} transition dipole moments were performed. Radiative lifetimes and vibronic branching ratios of radiative transitions from the (3)1{Pi} and (5)1{Sigma}+ states were evaluated. To elucidate the origin of the {Lambda}-doubling effect in the (3)1{Pi} state, the angular coupling (3)1{Pi}-(1-5)1{Sigma}+ electronic matrix elements were calculated and applied for the relevant q-factors estimate. The intensity distributions simulated for the particular (5)1{Sigma}+(3)1{Pi}-A-b LIF progressions have been found to be remarkably close to their experimental counterparts.
The 1:1:2 resonant elastic pendulum is a simple classical system that displays the phenomenon known as Hamiltonian monodromy. With suitable initial conditions, the system oscillates between nearly pure springing and nearly pure elliptical-swinging motions, with sequential major axes displaying a stepwise precession. The physical consequence of monodromy is that this stepwise precession is given by a smooth but multivalued function of the constants of motion. We experimentally explore this multivalued behavior. To our knowledge, this is the first experimental demonstration of classical monodromy.
A comprehensive study of the electronic states at the 4s+5s asymptote in KRb is presented. Abundant spectroscopic data on the astate state were collected by Fourier-transform spectroscopy which allow to determine an accurate experimental potential energy curve up to 14.8 AA . The existing data set (C. Amiot et al. J. Chem. Phys. 112, 7068 (2000)) on the ground state Xstate was extended by several additional levels lying close to the atomic asymptote. In a coupled channels fitting routine complete molecular potentials for both electronic states were fitted. Along with the line frequencies of the molecular transitions, recently published positions of Feshbach resonances in $^{40}$K and $^{87}$Rb mixtures (F. Ferlaino et al. Phys. Rev. A 74, 039903 (2006)) were included in the fit. This makes the derived potential curves capable for an accurate description of observed cold collision features so far. Predictions of scattering lengths and Feshbach resonances in other isotopic combinations are reported.
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