Transverse electron momentum distributions in strong-field ionization: nondipole and Coulomb focusing effects

Haram, Nida; Sang, R. T.; Litvinyuk, Igor

doi:10.1088/1361-6455/ab9272

Cited by 25 publications

(15 citation statements)

References 87 publications

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“…To date review articles on this topic have focussed mainly either on the fully relativistic regime or on photoionization in general [13]. The strong-field ionization was treated briefly with various theoretical methods to describe strong field ionization beyond the dipole approximation [14]. Further topical reviews exist for the fully relativistic case at extremely high intensities, again with the focus on theory, see e.g.…”

Section: Introductionmentioning

confidence: 99%

Ionization in intense laser fields beyond the electric dipole approximation: concepts, methods, achievements and future directions

Mäurer

Keller

2021

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

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The electric dipole approximation is widely used in atomic, molecular and optical physics and is typically related to a regime for which the wavelength is much larger than the atomic structure. However, studies have shown that in strong laser fields another regime exists where the dipole approximation breaks down. During the ionization process in intense laser fields and at long wavelengths the photoelectrons can reach higher velocities such that the magnetic field component of the laser field becomes significant. The ionization dynamics and the final momentum of the electron is therefore modified by the entire Lorentz force. In contrast the magnetic field interaction is neglected in the dipole approximation. Rapid developments in laser technology and advancements in the accuracy of the measurements techniques have enabled the observation of the influence of such non-dipole effects on the final angular photoelectron momentum distributions. More recently the number of studies on ionization beyond the dipole approximation has increased significantly, providing more important insight into fundamental properties of ionization processes. For example we have shown that the final three dimensional photoelectron momentum spectra is significantly affected by the non-dipole drift with the parent-ion interaction, the linear multiphoton momentum transfer on a sub-cycle time scale and the sharing of the transferred linear photon momenta between the electron and the ion. In this article we present an overview of the underlying mechanisms and we review the experimental techniques and the achievements in this field. We focus on ionization in strong laser fields in the regime where the dipole approximation is not valid but a fully relativistic description is not required.

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Section: Introductionmentioning

confidence: 99%

Ionization in intense laser fields beyond the electric dipole approximation: concepts, methods, achievements and future directions

Mäurer

Keller

2021

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

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“…Figure 1 shows the PMD in the plane spanned by the propagation and polarization directions of the laser for the first ATI peak, i.e., for the photon absorption channel with n = n 0 , see equation (9). Figure 1(a) shows the distribution in the dipole approximation, equation (12), while figure 1(b) shows the distribution obtained with the nondipole approach, equation (11). figure shows the energetically final with the dipole [equations ( 14)-( 15)] and nondipole [equations ( 19)-( 20)] approaches.…”

Section: Resultsmentioning

confidence: 99%

“…During the last decade, observations of nondipoleinduced shifts of the PMD along the laser propagation direction in strong-field ionization experiments [5][6][7][8][9] have fuelled interest as recently reviewed [10][11][12]. The experimental works [5][6][7][8][9] used pulsed lasers of femtosecond duration.…”

Section: Introductionmentioning

confidence: 99%

Nondipole photoelectron momentum shifts in strong-field ionization with mid-infrared laser pulses of long duration

Lund,

Madsen

2021

Preprint

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We consider atomic strong-field ionization in the long-pulse limit for linearly polarized infrared laser fields. We show how nondipole effects in the plane formed by the propagation and polarization directions lead to (i) a shift of the origin of the rings describing the energetically allowed final electron momenta for individual above-threshold ionization channels and (ii) a redistribution in the continuum population on each ring.

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“…Note in passing that nondipole effects have also been observed with near-infrared fields [51][52][53][54]; see Refs. [55][56][57] for recent reviews on nondipole effects in intense laser pulses. At near-infrared wavelengths the adiabaticity condition in Eq.…”

Section: Introductionmentioning

confidence: 99%

Nondipole effects in tunneling ionization by intense laser pulses

Madsen¹

2022

Preprint

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The limit of decreasing laser frequency can not be considered independently from nondipole effects due to increase in the laser-induced continuum electron speed in this limit. Therefore, in this work, tunneling ionization in the adiabatic limit is considered for an effective field that includes effects beyond the electric-dipole term to first order in 1/c, with c the speed of light. The nondipole term describes the interaction resulting from the electric dipole-induced velocity of the electron and the magnetic field component of the laser. The impact of this term on the ionization rate, tunnel exit point, momentum at the tunnel exit and electron dynamics is discussed. In the appropriate limit, the results of a nondipole strong-field approximation approach and those of the strict adiabatic limit, where time and field strength are parameters, are consistent. The nondipole strong-field approximation approach is used to identify nonadiabatic modifications of the initial conditions. The results open up an avenue to include nondipole effects in the initial tunneling ionization step in semiclassical models of strong-field and attosecond physics.

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Transverse electron momentum distributions in strong-field ionization: nondipole and Coulomb focusing effects

Cited by 25 publications

References 87 publications

Ionization in intense laser fields beyond the electric dipole approximation: concepts, methods, achievements and future directions

Ionization in intense laser fields beyond the electric dipole approximation: concepts, methods, achievements and future directions

Nondipole photoelectron momentum shifts in strong-field ionization with mid-infrared laser pulses of long duration

Nondipole effects in tunneling ionization by intense laser pulses

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