Laser modification of the exchange scattering in electron-atom collisions

Ferrante, G.; Leone, Cláudio; Trombetta, F.

doi:10.1088/0022-3700/15/13/011

Cited by 48 publications

(13 citation statements)

References 5 publications

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“…The present technique has been applied extensively to a variety of laser assisted electron atom collisions involving the transfer of one or several photons between the electron-atom system and the laser field in the cases of elastic, inelastic collisions and (e,2e) reactions. We neglect the exchanges effects in the presence work, since the field-free exchange effects are essentially negligible at the high impact energies considered here, and they are either smaller or slightly enhanced in the presence of a laser field [24].…”

Section: Introductionmentioning

confidence: 99%

Effects of laser polarization in laser-assisted electron-helium inelastic collisions: a Sturmian approach

Akramine¹,

Makhoute²,

Khalil³

et al. 1999

J. Phys. B: At. Mol. Opt. Phys.

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The influence of linearly and circularly polarized laser fields on the dynamics of fast electron-impact excitation in atomic helium is discussed. A detailed analysis is made in the excitation of 2 1 S, 3 1 S and 3 1 D dressed states of helium target. By using a semiperturbative treatment with the Sturmian basis expansion, we take into account the target atom distortion induced by a laser field. Important differences appear between the angular distributions depending on the different states of polarization, in particular the circular polarization presents an experimental interest. We give new features (intermediate resonances) for both polarizations, concerning the n = 2 states of helium for emission and the n = 3 for the absorption, in term of laser frequency. Qualitative differences from the case of laser-assisted elastic collisions have been evidenced.

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Section: Introductionmentioning

confidence: 99%

Effects of laser polarization in laser-assisted electron-helium inelastic collisions: a Sturmian approach

Akramine¹,

Makhoute²,

Khalil³

et al. 1999

J. Phys. B: At. Mol. Opt. Phys.

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“…2 that the inclusion of the exchange alters the magnitude ol the TDCS by lowering it significantly in comparison to that of the SBA without exchange; i.e., the TDCSs are mainly contributed by the exchange amplitude which shows that the exchange effects between two outgoing electrons cannot be ignored. This effect is manifested more clearly for an atomic system with more than one electron [55] and for slow velocities of the incident electron [54], Figure 3 shows our results of triple differential cross sections when the ionizing process is accompanied by the absorption of one photon ( l = 1). We observe that, for both laser polarization directions, the second Born approximation gives an enhanced binary peak and a reduced recoil peak in contrast to the results of the FBA.…”

Section: Resultsmentioning

confidence: 80%

“…It is well known from field-free electron-atom collision theory that exchange effects lose their importance when the velocity of the incoming electron is considerably larger than that of the atomic electrons [54], In order to demonstrate the importance of exchange effects, we have chosen to compare the corresponding second-order Born TDCSs results by including the exchange amplitude with the TDCSs generated singly by the direct amplitude. It can be seen from Fig.…”

Section: Resultsmentioning

confidence: 99%

Exchange effects and second-order Born corrections in laser-assisted(e,2e)collisions with helium atoms

et al. 2015

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The triple differential cross section for laser-assisted ionization of a helium target by slow electrons is analyzed within the framework of the second Born approximation. We evaluate the S-matrix elements using Volkov and Coulomb-Volkov wave functions for describing the continuum states of the scattered and the ejected electrons, respectively. The required scattering amplitudes are performed by expanding the atomic wave functions onto a complex-scaled Sturmian basis, which allows us to exactly take into account the contribution of the continuous spectrum to the dressing of the atomic states. Our results have been improved by taking into account exchange effects. Furthermore, the second-order Born correction is seen to be important and significantly affects the magnitudes of the binary and recoil peaks.

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“…In this calculation we have neglected the electron exchange effect between the projectile and the target electron in the final channel, which could be legitimate for such a LA process [16,28].…”

Section: Theorymentioning

confidence: 99%

Ionization of a lithium ion by electron impact in a strong laser field

2011

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The modification in the dynamics of the electron-impact ionization process of a Li + ion due to an intense linearly polarized monochromatic laser field (nγ e,2e) is studied theoretically using coplanar geometry. Significant laser modifications are noted due to multiphoton effects both in the shape and magnitude of the triple-differential cross sections (TDCSs) with respect to the field-free (FF) situation. The net effect of the laser field is to suppress the FF cross sections in the zeroth-order approximation [Coulomb-Volkov (CV)] of the ejected electron wave function, while in the first order [modified Coulomb-Volkov (MCV)], the TDCSs are found to be enhanced or suppressed depending on the kinematics of the process. The strong FF recoil dominance for the (e,2e) process of an ionic target at low incident energy is destroyed in the presence of the laser field. The FF binary-to-recoil ratio changes remarkably in the presence of the laser field, particularly at low incident energies. The difference between the multiphoton CV and the FF results indicates that for the ionic target, the Kroll-Watson sum rule does not hold well at the present energy range in contrast to the neutral atom (He) case. The TDCSs are found to be quite sensitive with respect to the initial phase of the laser field, particularly at higher incident energies. A significant qualitative difference is noted in the multiphoton ejected energy distribution (double-differential cross sections) between the CV and the MCV models. Variation of the TDCSs with respect to the laser phase is also studied.

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Laser modification of the exchange scattering in electron-atom collisions

Cited by 48 publications

References 5 publications

Effects of laser polarization in laser-assisted electron-helium inelastic collisions: a Sturmian approach

Effects of laser polarization in laser-assisted electron-helium inelastic collisions: a Sturmian approach

Exchange effects and second-order Born corrections in laser-assisted(e,2e)collisions with helium atoms

Ionization of a lithium ion by electron impact in a strong laser field

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