Molecule ultracold

Figure 8.6 Collisions of ultracold molecules in a quasi-2D geometry. Presented are the rates of the loss of molecules from an optical lattice trap occurring due to chemical reactions. The squares represent the reactions of molecules prepared in the same (translational and internal) quantum states the circles are for collisions of molecules in different translational states but the same internal states the triangles are for molecules in different internal states. Adapted with permission from Ref. [1].

The significance of resonantly enhanced two-photon association stems from the visibility of using it to form ultracold molecules, a topic of considerable interest. fSr cooling schemes that work for atoms [338-340] tend to fail for molecules, ily due to the presence of many near-resonance lines and the presence of other ges, of freedom, in addition to translation (rotations, vibrations, etc.), that must... 

IX. Intramolecular Vibrational Redistribution (IVR) in Ultracold Molecules in Supersonic Beams... 

IX. INTRAMOLECULAR VIBRATIONAL REDISTRIBUTION (IVR) IN ULTRACOLD MOLECULES IN SUPERSONIC BEAMS... 

A. Vardi, D. Abrashkevich, E. Frishman, M. Shapiro, Theory of radiative recombination with strong laser pulses and the formation of ultracold molecules via stimulated photorecombination of cold atoms, J. Chem. Phys. 107 (1997) 6166. 

P. PiUet, F. Masnou-Seeuws, A. CrubeUer, Molecular photoassociation and ultracold molecules, in Atomic and Molecular Beams, ed. by R. Campargue (Springer, Berlin, 2001),... 

An understanding of atomic and molecular interactions and collisions is essential to the study of cold and ultracold molecules. Collisions govern the lifetime of molecules in traps and determine whether proposed cooling schemes will work. Once atoms and molecules are in the ultracold regime, the extent to which their interactions can be controlled depends on a detailed understanding of their collisional properties. The purpose of this chapter is to outline atomic and molecular collision theory and describe the special features that are important to the study of cold molecules. 

Collisions in applied electric and magnetic fields are important for several reasons. Most importantly, applied fields provide ways to control ultracold gases, and for atomic systems this control has already led to the observation of a wide range of new phenomena including molecule formation and transitions to superfluid phases [45]. There is little doubt that applied fields will provide the key to controlling the much richer behavior expected for ultracold molecules. 

Although such systems have been extensively studied at higher collision energies over the last few deeades, the new experimental breakthroughs in creating dense samples of cold and ultracold molecules have provided unprecedented opportunities to explore elastic, inelastic, and reactive collisions at temperatures close to absolute zero. These studies have revealed unique aspects of molecular collisions and energy transfer mechanisms that are otherwise not evident in thermal energy collisions. 

The quantitative description of ultracold molecule-molecule collisions is another challenging topic. The recent progress on the H2-H2 system will be difficult to implement for heavier systems due to the large number of rovibrational levels of the molecules. The study of H2-H2 collisions has shown that, for certain combinations of rovibrational levels, the energy transfer may occur to specific final rovibrational states. In such cases, the calculations can use a much smaller basis set without compromising the accuracy. 

Quemener, G., Balakrishnan, N., and Krems, R.V., Vibrational energy transfer in ultracold molecule-molecule colUsions, Phys. Rev. A, 77, 030704(R), 2008. 

Mark, M., Kraemer, T., Waldburger, P, Herbig, J., Cbin, C., Nagerl, H.-C., and Grimm, R., Stiickelberg interferometry with ultracold molecules, Phys. Rev. Lett., 99, 113201,2007. 

However, it is theoretically predicted and experimentally established that at small detunings, one-color PA followed by spontaneous emission forms X and a state ultracold molecules in very high vibrational levels, as discussed in Section 5.2.1. For example, in Rb2, theX E+ state levels v" = 111-117 (within 13cm of dissociation) are observed [33], Even higher levels are also predicted to form, but are quickly photodissociated in the experiment. Virtually no population goes to v" = 0 and in K2, the v" = 35 and 36 levels (bound by 1900 cm ) are the... 

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