Laser-dipole interaction

The rotational relaxation times of these nitrocompounds have not been measured. Comparison with the studies of perylene by Klein and Haar [253] suggests that most of these nitrocompounds have rotational times 10—20 ps in cyclohexane. For rotational effects to modify chemical reaction rates, significant reaction must occur during 10ps. This requires that electron oxidant separations should be <(6 x 10-7x 10-11)J/2 2 nm. Admittedly, with the electron—dipole interaction, both the rotational relaxation and translational diffusion will be enhanced, but to approximately comparable degrees. If electrons and oxidant have to be separated by < 2 nm, this requires a concentration of > 0.1 mol dm-3 of the nitrocompound. With rate coefficients 5 x 1012 dm3 mol-1 s 1, this implies solvated electron decay times of a few picoseconds. Certainly, rotational effects could be important on chemical reaction rates, but extremely fast resolution would be required and only mode-locked lasers currently provide < 10 ps resolution. Alternatively, careful selection of a much more viscous solvent could enable reactions to show both translational and rotational diffusion sufficiently to allow the use of more conventional techniques. 

Optical response of a material is generally described in the approximation of electric-dipole interaction with the radiation ( 0. In this model, the oscillating electric field of radiation induces a polarization in the medium. When a material is subject to a strong optical pulse from a laser the electric field is intense and the... 

The interaction V considered here is the dipole interaction of the system with the applied radiation field of the probing laser, i.e.,... 

Shining properly chosen short laser pulses onto cold clouds of atomic Cs or lib can reveal a fascinating world where microsecond is as long as eternity for one kind of motion and extremely short for another whereas the highly excited atoms almost do not move, excitations exchanged via their dipole-dipole interactions can jump from one atom to another and travel over the sample. How do coherent phenomena occur here and what are the effects of decoherence ... 

Abstract We consider a possible realization of the position- and momentum-correlated atomic pairs that are confined to adjacent sites of two mutually shifted optical lattices and are entangled via laser-induced dipole-dipole interactions. The Einstein-Podolsky-Rosen (EPR) "paradox" [Einstein 1935] with translational variables is then modified by lattice-diffraction effects. We study a possible mechanism of creating such diatom entangled states by varying the effective mass of the atoms. 

In the second paper, O Dell et al discuss Bose-Einstein condensates with laser-induced dipole-dipole interactions. A Bose-Einstein condensate formed in a trapped ultracold atomic vapour constitutes an example of macroscopic... 

BOSE-EINSTEIN CONDENSATES WITH LASER-INDUCED DIPOLE-DIPOLE INTERACTIONS... 

Abstract We consider the interparticle correlations in a gaseous Bose-Einstein condensate which has laser-induced dipole-dipole interactions. These correlations, which are tunable and occur at the length scale of the laser wavelength, can lead to a roton minimum in the excitation spectrum. 

Bose-Einstein condensates with laser-induced dipole-dipole interactions... 

Figure 2. The Bogoliubov dispersion relation (scaled by the recoil energy of an emitting atom) for short-range s-wave scattering (dashed line) can be modified by the dipole-dipole interaction to the extent that is displays a roton minimum (solid line). Parameters laser wavelength and scaled intensity Al = 795 nm, I = 0.057, BEC radius and density wr = 3.5 Al, 8.1020 atoms.m-3, s-wave scattering length due to van der Waals interaction 5.5 nm.

Here f is the interatomic axis, and Vzz is the component of the retarded dipole-dipole interaction tensor generated by the linearly z-polarized laser light... 

In the absence of the driving laser field and the dipole-dipole interaction, the basis states of the two-atom system are the four direct products states... 

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