Inclusion of Coulomb effects in laser-atom interactions

Abstract

We investigate the role of the Coulomb interaction in strong field processes. We find that the Coulomb field of the ion makes its presence known even in highly intense laser fields, in contrast to the assumptions of the strong field approximation. The dynamics of the electron after ionization is analyzed with four models for an arbitrary laser polarization: the Hamiltonian model in the dipole approximation, the strong field approximation, the Coulomb-corrected strong field approximation and the guiding center. These models illustrate clearly the Coulomb effects, in particular Coulomb focusing and Coulomb asymmetry. We show that the Coulomb-corrected strong field approximation and the guiding center are complementary, in the sense that the Coulomb-corrected strong field approximation describes well short time scale phenomena (shorter than a laser cycle) while the guiding center is well suited for describing long time scale phenomena (longer than a laser cycle) like Coulomb-driven recollisions and Rydberg state creation.

Triggering recollisions with XUV pulses: Imprint of recolliding periodic orbits

“…Figure 7 shows the final distance of the electron as a function of its initial conditions (x, p y ) for y = p x = 0 for an integration time of 10 laser cycles and I = 3 × 10 14 W • cm −2 . We observe sensitivity with respect to the initial conditions as a signature of recollisions [15]. We refer to these regions as recolliding regions in phase space.…”

“…Various perturbative [15,22,42] and non-perturbative [3,29] methods have been developed in order to include the Coulomb interactions in the trajectory analyses. In particular, the study of periodic orbits in phase space has been used to understand and predict various highly nonlinear phenomena by fully taking into account the strong laser and Coulomb interactions.…”

Semiclassical approach for solving the time-dependent Schrödinger equation in spatially inhomogeneous electromagnetic pulses

“…This combination of the two previous examples in Secs. III A and III B constitutes the Coulomb-Volkov problem, for which merely approximate solutions [65][66][67][68], but no analytical wavefunction are known. We assume a laser pulse with 15 eV central photon energy, a cosinesquare temporal intensity envelope with a pulse length of 0.5 fs full width at half intensity maximum (FWHIM), and 3 × 10 15 W/cm 2 peak intensity.…”

Using analytically-corrected semiclassical rescattering model to study Coulomb impact in spiderlike photoelectron momentum distributions

“…There have been theoretical approaches dealing with the Coulomb interaction or the Coulomb correction in strong field ionization. They include the quantum trajectory Monte Carlo (QTMC) theory [63], perturbational methods along electron's trajectory [10,[64][65][66][67][68], and the two-step model [69,70] and so on. The QTMC needs a lot of computations for an ensemble and cannot treat the under-barrier dynamics, while the perturbational methods can also be computationally involved in solving the inverse problem [10] and the Coulomb potential always becomes divergent or singular when the electron returns exactly to the parent ion.…”