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We present a detailed theoretical and experimental study of Feshbach resonances in the Li-K mixture. Particular attention is given to the inelastic scattering properties, which have not been considered before. As an important example, we thoroughly investigate both elastic and inelastic scattering properties of a resonance that occurs near 155 G. Our theoretical predictions based on a coupled channels calculation are found in excellent agreement with the experimental results. We also present theoretical results on the molecular state that underlies the 155 G resonance, in particular concerning its lifetime against spontaneous dissociation. We then present a survey of resonances in the system, fully characterizing the corresponding elastic and inelastic scattering properties. This provides the essential information to identify optimum resonances for applications relying on interaction control in this Fermi-Fermi mixture. [ABSTRACT FROM AUTHOR]

Over 100 high lying level energies of the lowest electronic states X¹Σg+ and a³Σu+ in Cs2 are determined in a A-like scheme two-colour photoassociation spectroscopy. The results are analyzed with a coupled channel model using an asymptotic approach, based on nodal lines. From this analysis we determine the long range dispersion coefficient C6 to 6846.2±15.6 a.u. We also obtain the first experimental determination of the amplitude of the asymptotic exchange term. [ABSTRACT FROM AUTHOR]

We investigate the influence of a laser field, which is near-resonant to the atomic sodium 3²P1/2 → 3²D3/2 transition, on the last bound levels of the A¹Σu+ state in Na2. In a molecular beam experiment level shifts up to ≈ 100 MHz and light induced line broadenings were observed using an optical double resonance excitation scheme. Moreover, the coupling laser can reduce the number of bound levels of the A state by one or more units, which effectively means that in the picture of a collision of a 3²S1/2 and a 3²P1/2-atom the scattering phase is altered by more than π. The observed effects are interpreted as light induced couplings of the A¹Σu+ state, which correlates to the 3s1/2 + 3p1/2 asymptote, to the 4¹Σg+ and 2¹Πg states at the 3s1/2 + 3d3/2 asymptote. We performed multi-channel calculations, applying the mapped Fourier grid method, which reproduce our experimentally observed level shifts well. [ABSTRACT FROM AUTHOR]

We report on the first observation of the outer well of the (6)¹ Σg+ state of Na2 molecule. The levels are populated in a molecular beam experiment with a three step laser excitation. The fact that these levels predissociate allows an almost background free detection by the appearance of atomic fluorescence. With this method almost all vibrational levels of the outer well are observed. The corresponding predissociation line widths show an oscillating behaviour. The theoretical description of the predissociation is presented in the framework of mapped Fourier grid Flamiltonian representation with optical potential, involving two coupled electronic states. Combining the spectroscopic information on energy positions and predissociation widths, a Rydberg-Klein-Rees potential curve is given for the outer well. Such a state could offer a reliable path for photoassociation of cold Na atoms and formation of ultracold Na2 molecules. [ABSTRACT FROM AUTHOR]

We show first results and systematic investigations of a matter wave interferometer with the K2 molecule, using a transition between the electronic ground state X and the state b . This spin forbidden transition is observable due to spin-orbit coupling between the states b and A . The experimental results are compared with numerical simulations, which show the power of the interferometer to observe small phase shifts by weak interactions. [ABSTRACT FROM AUTHOR]

A simple model is developed to determine a scattering length from the experimental values of the energy of the last, least bound, vibrational levels of the ground state, either or ,of an alkali dimer. It is based on an extrapolation of the positions of the few outermost nodes of the bound vibrational wave functions towards the dissociation threshold. It uses the asymptotic part of the molecular potential only. The method is applied to recently measured levels at the asymptote (3 s+3 s) of Na2. We obtain precise values for the two scattering lengths respectively associated to the dissociation limits F 1= F 2=1, F=2 (55.1 1.6 a0) and F 1= F 2=1, F=0 (50.0 1.6 a0); the first value corresponds to the a1,-1 scattering length usually considered in cold collisions. The extrapolation procedure is also applied to Li2, using existing experimental data. [ABSTRACT FROM AUTHOR]

The photoassociative spectroscopy of the Cs2 0 g - long-range molecular state dissociating into the asymptote is performed, using cold cesium atoms in a vapor-cell magneto-optical trap (MOT). Vibrational levels from v =0 to v =132 are identified, and their rotational structure is well resolved up J =8 for levels below v =74. These data are analyzed in terms of the Rydberg-Klein-Rees (RKR) procedure, and correspond to 99.6% of an effective potential curve with a minimum at Å and a cm-1 depth. Both ab initio calculations and simple model estimations predict a double-well structure for this potential curve, which cannot be reproduced presently by the RKR approach but which is confirmed by the presence of giant structures in the spectrum. The 1u( )long-range state is also observed for the first time in Cs2. [ABSTRACT FROM AUTHOR]

Due to competition between ionic and covalent dissociation, the excited potential curves of the alkali dimers display long range structures, leading in some cases to secondary wells. We discuss the possibility of populating the well (with a depth of 1614.8 cm-1, located at R e= 30.5 a 0) that is present in the Na2 potential curve and propose detection schemes. [ABSTRACT FROM AUTHOR]