Thermal Relaxation of Adsorbed Atoms in an Intense Laser Field.
STATE UNIV OF NEW YORK AT BUFFALO DEPT OF CHEMISTRY
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Adsorbed atoms on the surface of a harmonic lattice are immersed in a strong laser field. The optical Bloch equations are derived, which include the thermal relaxation and the coherent excitation of the adbond. This is accomplished by a transformation to dressed states, which diagonalizes the interaction with the laser. The single phonon couplings are then understood as transitions between dressed states. The radiative contributions for arbitrary strong fields are obtained in the master equation, and it is shown that the coherences with respect to the dressed states decay exponentially, due to the phonon relaxation. General properties of the competing phonon induced redistribution and optical excitation of the level populations are presented, and exemplified by an explicit elaboration of a three level system. The results are amenable to analytical evaluation once the interaction potential is prescribed, and extensions of the approach to include multiphonon processes are straightforward.
- Radiation and Nuclear Chemistry
- Atomic and Molecular Physics and Spectroscopy