Laser-assisted symmetric charge transfer in atomic collisions

Ferrante, G.; Casico, L Lo; Spagnolo, Bernardo

doi:10.1088/0022-3700/14/20/020

Cited by 13 publications

(8 citation statements)

References 16 publications

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“…The reported experiments on laser-assisted collisions [4] involve one-photon processes and thermal collision energies. Also, theoretical descriptions [5] have mostly been limited to slow collisions and/or relatively weak fields. Recently, however, the theoretical works by Madsen et al [6] and by Kirchner [7] investigate fast collisions in the presence of a strong laser field.…”

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confidence: 99%

Ultrahigh Harmonics from Laser-Assisted Ion-Atom Collisions

Lein

Rost

2003

Phys. Rev. Lett.

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We present a theoretical analysis of high-order harmonic generation from ion-atom collisions in the presence of linearly polarized intense laser pulses. Photons with frequencies significantly higher than in standard atomic high-harmonic generation are emitted. These harmonics are due to two different mechanisms: (i) collisional electron capture and subsequent laser-driven transfer of an electron between projectile and target atom; (ii) reflection of a laser-driven electron from the projectile leading to recombination at the parent atom.PACS numbers: 42.65. Ky,34.50.Rk,32.80.Rm,34.70+e Over the last decades, a vast amount of work has been devoted to the study of ion-atom collisions [1] Kirchner [7] investigate fast collisions in the presence of a strong laser field. In Ref.[6], excitation mechanisms are discussed, while Ref. [7] focuses on ionization and electron capture. In both cases, the presence of the field leads to a significant modification of the collision process. On the other hand, there has been no study on the question how typical strong-field processes in atoms, such as high-order harmonic generation (HHG) [8] and above-threshold ionization [9], are modified due to the impact of an ion projectile. In HHG, a large number of incoming laser photons are converted into a single high-energy photon. HHG experiments are presently pursued with great effort [10,11] since the process serves as a source of coherent XUV radiation and attosecond pulses.In the present work, we investigate HHG in laserassisted ion-atom collision. We focus on impact velocities such that the time-scales of nuclear and electronic motion are comparable, i.e., we have significant probabilities for collisional electron transfer from the target to the projectile. For sufficiently long laser pulse durations, the laser-driven electron effectively sees a large range of internuclear distances during one laser pulse. When the laser polarization axis is parallel to the ion impact velocity, we show that this situation results in the generation of high harmonics with photon energies much higher than usually obtained in atomic HHG.The classical recollision model [12] describes atomic HHG as a sequence of strong-field ionization, acceleration of the electron in the laser field and recombination with the core. Within this model, the maximum return energy of the laser-driven electron is 3.17U p where2 ) is the ponderomotive potential for a laser with field amplitude E 0 and frequency ω. The maximum energy of the emitted photons is then equal to 3.17U p +I p where I p is the atomic ionization potential. For ion-atom collisions, we show below how the interplay between collisional electron capture and laser-driven electron transfer between target and projectile leads to new mechanisms of HHG with cutoffs at significantly higher energies.We consider collisions of protons on hydrogen atoms for proton energies of 2 keV (impact velocity v = 0.283 a.u.). Due to the large impact momentum, the projectile trajectory is assumed to be classical and along a s...

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confidence: 99%

Ultrahigh Harmonics from Laser-Assisted Ion-Atom Collisions

Lein

Rost

2003

Phys. Rev. Lett.

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“…When an asymmetric collision occurs between an ion and an atom in the presence of an intense laser, the collision cross-section for the charge transfer induced by the laser can be several orders of magnitude greater than when it occurs without the presence of the laser (Anis et al (2006); Cabrera-Trujillo (2009); Copeland & Tang (1976)). In the first theoretical works on charge transfer induced by laser in a collision, the attention focused in resonant effects where the frequency of the laser was tuned to a transition in the colliding system (Copeland & Tang (1976); Ferrante et al (1981); Gudzenko & Yakovenko (1972); Pindzola et al (2003)). These calculations were carried out for very small intensities, or by means of perturbative calculations or for systems that could be considered coupled by two states in the presence of a laser field (Errea et al (1983)).…”

Section: Laser Assisted Charge Transfer Collisionsmentioning

confidence: 99%

Lasers in Atomic Collisions, Cold Plasma and Cold Atom Physics

Cabrera‐Trujillo¹,

Jiménez-Mier²,

Juarez³

2011

Femtosecond-Scale Optics

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“…Further theoretical studies (2)(3)(4)(5) were continued during the 1980s. Recent progress in experimental *Email: trujillo@fis.unam.mx…”

Section: Introductionmentioning

confidence: 99%

“…Since the early work of Gudzenko and Yakovenko (1), most attention has been focused on resonant effects where the laser frequency was tuned to some transition in the collision system (2,5,10). For ion-atom collision in the presence of an intense laser field, the laser-induced charge exchange cross-section can become several orders of magnitude larger than the corresponding collision-induced charge exchange cross-section (5).…”

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confidence: 99%

Laser and isotope effects in charge transfer processes in atomic collisions

Cabrera‐Trujillo

2009

Radiation Effects and Defects in Solids

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Charge transfer processes are fundamental to the understanding of matter neutralization in atomic and molecular processes. Due to the polarizability of the material, charge transfer can be enhanced or suppressed during the interaction with electromagnetic radiation. Furthermore, charge transfer has different contributions arising from the radial and rotational regions of the potential interaction in the collision, which depend on the mass of the target and projectile. Since these effects appear in a very short time (femtoseconds), the dynamics must be carried out outside the Born-Oppenheimer approximation. In this work, we present charge transfer results for He 2+ ions colliding with atomic hydrogen and tritium atoms for collision energies from 100 eV/amu up to 1.5 keV/amu, assisted by a fast, short laser pulses of intensity 3.5 × 10 12 W/cm 2 and wave length of 790 nm by means of an electron-nuclear dynamic treatment. We find large isotope effects in the low-energy region up to one order of magnitude in the charge transfer cross-section in the absence of the laser pulse. In the presence of the laser pulse, the isotope effect is negligible and the charge transfer cross-section is enhanced up to two orders of magnitude in the low-energy region.

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Laser-assisted symmetric charge transfer in atomic collisions

Cited by 13 publications

References 16 publications

Ultrahigh Harmonics from Laser-Assisted Ion-Atom Collisions

Ultrahigh Harmonics from Laser-Assisted Ion-Atom Collisions

Lasers in Atomic Collisions, Cold Plasma and Cold Atom Physics

Laser and isotope effects in charge transfer processes in atomic collisions

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