Relativistic electronic dressing

We study the effects of the relativistic electronic dressing in laser-assisted electron-hydrogen atom elastic collisions. We begin by considering the case when no radiation is present. This is necessary in order to check the consistency of our calculations and we then carry out the calculations using the relativistic Dirac-Volkov states. It turns out that a simple formal analogy links the analytical expressions of the differential cross section without laser and the differential cross section in presence of a laser field.Comment: 11 pages, 18 figures, Late

Simulation of simultaneous photonic and phononic band gaps in Sapphire

The simultaneous existence of photonic and phononic band gaps in a simple square periodic array of holes drilled in sapphire substrate is investigated theoretically. The investigations are focused in a first part on a photonic gap obtaining with a phononic gap in the same time making use of some specific parameters. In the second part, using a cavity defect in which the strong confinement of acoustic and optic waves enhances the interaction, we obtain photonic and phononic modes classified according to their symmetry (even or odd), also allowed bands in gaps, which has led to the propagation of waves appropriate. The frequencies of the localized modes in the first band gap are computed with a finite element method

Electron-atomic-hydrogen elastic collisions in a laser field

The differential cross-section for electron-hydrogen atom collisions in the presence of a linearly polarized laser field is studied as a function of a scattering angle of low energy electron by employing second-Born approximation (SBA). Detailed analysis is performed in no forward scattering angle

Simulation of simultaneous photonic and phononic band gaps in Sapphire

The simultaneous existence of photonic and phononic band gaps in a simple square periodic array of holes drilled in sapphire substrate is investigated theoretically. The investigations are focused in a first part on a photonic gap obtaining with a phononic gap in the same time making use of some specific parameters. In the second part, using a cavity defect in which the strong confinement of acoustic and optic waves enhances the interaction, we obtain photonic and phononic modes classified according to their symmetry (even or odd), also allowed bands in gaps, which has led to the propagation of waves appropriate. The frequencies of the localized modes in the first band gap are computed with a finite element method

Polarisation effect of laser field in inelastic electron - hydrogen collisions

We study the influence of the laser polarization on the electron impact excitation of atomic hydrogen. Our method takes into account the "dressing" of the target states by including the laser-atom interaction to first order time-dependent perturbation theory, while the interaction of the laser field with the incident electron is treated to all orders by using the non relativist Volkov function. The interaction of the fast projectile with the target atom is treated in the first Born approximation. The calculations are performed via two distinct computations. The first one is based on a direct calculation, the second based on a Sturmian approach. Important differences appear between the angular distributions depending on the polarization chosen