| Abstract: |
- The possibility to create extremely short pulses, using high-order harmonics created by a low-frequency
driving field, has stimulated studies of photo induced dynamics in the low-frequency regime. Using lowfrequency
- driver lasers for high-order harmonic generation (HHG) is attractive because the cut-off limit
scales as one over the laser frequency squared. However, the low frequency raised challenges in dynamics
calculation in this regime.The multiphoton absorptions by molecules in strong laser fields depend on the
polarization of the laser and on the molecular structure.
We represent a perturbational approach for the calculations of the quasi-energy spectrum in the low
frequency regime, that avoids the construction of the Floquet operator with extremely large number of
Floquet channels. The zero-order Hamiltonian in our perturbational approach is the adiabatic Hamiltonian
where the atoms/molecules are exposed to a dc electric field rather than to ac-field. The second order
perturbation correction terms are obtained when -
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