The interaction of excited atoms and few-cycle laser pulses (original) (raw)
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The role of light ellipticity in ionization of atoms by intense few-cycles laser pulses
We provide theoretical investigations of the response of the Ar and H atoms to an intense elliptically polarized few-cycle laser pulse, as a function of light ellipticity. The time-dependent Schr{\"o}dinger equation describing the least-bound electron is solved numerically, and differential quantities such as the momentum distribution, the electron density in the continuum, and the above-threshold ionization spectra are computed. These quantities provide insight into the ionization dynamics and the electron rescattering process as a function of light ellipticity, and reveal great similarities between the response of Ar and H to the applied external field.
Physical Review A, 2019
Exchange correlation plays an important role in double-ionization of complex atoms by ultrashort laser pulse. In this work, we investigate two-photon double inner-shell electron ionization of neon induced by an attosecond extreme ultraviolent pulse in the framework of the quantum master equation. Our simulations reveal a distinct non-sequential effect via broadened double peaks, as a result of energy sharing between the two ionized electrons. When dissipation is included to show the interplay of coherence and decoherence, the two-photon double-ionization scaling law breaks down. We further study the total cross section of 2s 2 double ionization as a function of photon energy in both non-sequential and sequential regions.
Dynamics of interactions of short laser pulses with atoms: role of close-coupling effects
Journal of Physics B: Atomic, Molecular and Optical Physics, 2001
The processes of ionization and excitation of hydrogen atoms by short laser pulses are studied using the close-coupling analysis, without discretization of the continuum. The influence of transitions through the excited discrete states on formation of the electron energy spectra is studied. The resonance structures in ionization probabilities are given at different values of the laser field parameters. Electron energy spectra are calculated for the pulses with linear and circular polarization.
Physical Review A, 2006
Electron-momentum distributions for above-threshold ionization of argon in a few-cycle, linearly polarized laser pulse are investigated. Spectral features characteristic of multiphoton as well as tunneling ionization coexist over a range of the Keldysh parameter ␥ in the transition regime ␥ ϳ 1. Surprisingly, the simple strong-field approximation ͑SFA͒ is capable of reproducing the key features of the two-dimensional momentum distributions found in the full solution of the time-dependent Schrödinger equation, despite the fact that SFA is known to severely underestimate the total ionization probability.
A new physical mechanism for the onset of atomic ionization in an optical field with jolts of phase
arXiv (Cornell University), 2022
A theoretical model that describes a new mechanism of atomic and molecular ionization in a low intensity electromagnetic wave (light or laser beam) with the energy of quanta that is lower than required for a single photon ionization is presented. The essence of the proposed physical mechanism is the step-like gain of energy of a bound electron that occurs every time the phase of the electromagnetic field jolts. Providing there is sufficiently large number of the phase jolts, the summation of the step increases of the electron oscillation energy can render the total energy of the bound electron such that it exceeds the ionization potential.
Ionization of a single hydrogen-like atom by laser pulse of near-atomic strength
2007
The dynamics of high-harmonic generation and atom ionization by a strong and superstrong laser field are studied. In contrast to many earlier works, the present theory does not impose limitations on the laser field's strength. We solve the nonrelativistic problem of a single hydrogen-like atom's ionization from the ground state by a short laser pulse of subatomic, atomic, and superatomic field strength. Within the framework of the proposed method, we investigated the matrix elements of the ionization transition and revealed its substantially nonlinear dependence on the laser field strength. Both ionization and recombination processes are taken into account. The proposed method enables us to take into account the arbitrary order multiphoton ionization processes.
Two-electron atoms in short intense laser pulses
Physical Review A, 1998
We discuss a method of solving the time dependent Schrödinger equation for atoms with two active electrons in a strong laser field, which we used in a previous paper [ A. Scrinzi and B. Piraux, Phys. Rev. A 56, R13 (1997) ] to calculate ionization, double excitation and harmonic generation in Helium by short laser pulses. The method employs complex scaling and an expansion in an explicitly correlated basis. Convergence of the calculations is documented and error estimates are provided. The results for Helium at peak intensities up to 10 15 W/cm 2 and wave length 248 nm are accurate to at least 10 %. Similarly accurate calculations are presented for electron detachment and double excitation of the negative hydrogen ion.
Physical Review A
We study strong field molecular ionization using few (4-10) cycle laser pulses. Employing a supercontinuum light source, we are able to tune the optical laser wavelength (photon energy) over a range of about ∼200 nm (500 meV). We measure the photoelectron spectrum for a series of different molecules as a function of laser intensity, frequency, and bandwidth and illustrate how the ionization dynamics vary with these parameters. We find that multiphoton resonances and nonadiabatic dynamics (internal conversion) play an important role and result in ionization to different ionic continua. Interestingly, while nuclear dynamics can be "frozen" for sufficiently short laser pulses, we find that resonances strongly influence the photoelectron spectrum and final cationic state of the molecule regardless of pulse duration-even for pulses that are less than 4 cycles in duration.