Laser induced photoassociation

Thorsheim HR, Weiner J, Julienne PS (1987) Laser-induced photoassociation of ultracold sodium atoms. Phys Rev Lett 58 2420-2423... 

Thorsheim H R, Weiner J and Juiienne P S 1987 Laser-induced photoassociation of ultracold sodium atoms Phys.Rev.Lett. 58 2420-3... 

The goal of this book is to present in a coherent way the problems of the laser control of matter at the atomic-molecular level, namely, control of the velocity distribution of atoms and molecules (saturation Doppler-free spectroscopy) control of the absolute velocity of atoms (laser cooling) control of the orientation, position, and direction of motion of atoms (laser trapping of atoms, and atom optics) control of the coherent behavior of ultracold (quantum) gases laser-induced photoassociation of cold atoms, photoselective ionization of atoms photoselective multiphoton dissociation of simple and polyatomic molecules (vibrationally or electronically excited) multiphoton photoionization and mass spectrometry of molecules and femtosecond coherent control of the photoionization of atoms and photodissociation of molecules. 

Fig. 8.7 Laser-induced photoassociation (a) resonant excitation of the colliding cold atoms to an electronically excited state of a molecule (b) single-photon photoassociation of ultracold K2 atoms yields translationally ultracold molecules in vibrationaJly excited levels of the electronic ground state. (Reprinted with courtesy and permission of the American Physical Society from Nikolov et al. 1999.)...

The most interesting implementations and applications of laser-induced photoassociation of ultracold atoms have emerged in experiments with quantum gases (BECs and Fermi-degenerate gases). These experiments made it possible to obtain and investigate molecular quantum gases. They are briefly discussed in Section 8.5. 

In short, photoassociation spectroscopy of cold trapped atoms is a very powerful tool for exploring molecular energy levels heretofore inaccessible to conventional spectroscopy. This technique owes its advent to the development of two effective laser methods for controlling atoms and molecules, namely, laser-induced photoassociation and laser-induced photoionization. 

Inoue G, Ku J K and Setser D W 1982 Photoassociative laser induced fluorescence of XeCI J.Chem.Phys. 76 733-4... 

Inoue G, Ku JK, Setser DW. (1982) Photoassociative laser induced fluorescence of XeCl. J. Chem. Phys. 76 733-734. 

Fig. 8.10 Laser-induced Feshbach resonance scattering length a (in terms of the Bohr radius ao) (solid line) and inelastic-collision rate coefficient Ainei (dashed line) as a function of the detiming of the laser from the photoassociation resonance for typical parameters of Inset schematic diagram of the optical coupling of the scattering unbound state A with the excited bound state B. (Reprinted from Theis et al. 2004 with courtesy and permission of the American Physical Society.)...

The KRb experiments take place in a dual-species vapor-cell MOT [45]. Diode lasers at 767 and 780 nm are used to cool and trap K and Rb atoms, respectively, in the dark-spot MOT configuration. Atomic densities of 3 x lO cm" for K and 1 x 10 cm for Rb are realized, with corresponding temperatures of 300 and 100 tiK. Photoassociation is induced by illuminating the overlapping cold atomic clouds with light from a tunable cw titanium-sapphire laser (Coherent 899-29). This laser typically provides 500 mW with a linewidth of 1 MHz and its output is focused down to approximately match the size ( 300 p,m diameter) of the cold atom clouds. 

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