Pump, diffusion Quantum

The first two mechanisms represent bulk effects, and the latter is related to the surface. The contribution of these mechanisms into the total diffraction efficiency depends on many parameters, including the extinction coefficient at a particular wavelength of a laser beam, the quantum yield of the photochemical isomerization, the temperature-dependent relaxation time of the cis-isomers, the angular diffusion, or even the film confinement conditions. To elucidate the mechanism of photorecording, and to optimize the conditions for readout of recorded data, different polarization geometries of the interfering pump beams can be chosen. ... 

A theory for the ultrafast pump-probe spectroscopy of large polyatomic molecules in condensed phases was developed in the work [15]. A multimode Brownian oscillator model was used to account for high-frequency molecular vibrations and local intermolecular modes as well as collective solvent motions. A semiclassical picture was provided using the density matrix in Liouville space. Conditions for the observation of quantum beats, spectral diffusion, and solvation dynamics (dynamic Stokes shift) are specified. 

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