Laser-induced non-sequential double ionization investigated at and below the threshold for electron impact ionization

Eremina, E.; Liu, X.; Rottke, H.; Sandner, W.; Dreischuh, A.; Lindner, Fabrizio; Grasbon, F.; Paulus, Gerhard G.; Walther, H.; Moshammer, R.; Feuerstein, B.; Ullrich, J.

doi:10.1088/0953-4075/36/15/308

Cited by 102 publications

(113 citation statements)

References 40 publications

(55 reference statements)

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“…Not really seen in Fig. 2(a) and also not in all previous experiments [7,11], not much attention was paid to that fact until now, however, partly because the spectra were always blurred by REDI in quadrants 1 and 3.…”

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confidence: 80%

“…Accordingly, only few differential studies have been reported on NSDI [11][12][13][14][15] close to threshold. In just one coincidence measurement [13], to the best of our knowledge, the energy of the recolliding electron was below the phase-dependent, field-modified ionization potential [12] I P I P ÿ 2 2jE 0 cos !t r j 1=2 , i.e., below the electron-impact ionization threshold (I P , ionization potential of the ion; !t r , phase of the laser field where recollision occurs).…”

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confidence: 99%

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Strong-Field Double Ionization of Ar below the Recollision Threshold

et al. 2008

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Nonsequential double ionization of Ar by 45 fs laser pulses (800 nm) at 4-7 10 13 W=cm 2 was explored in fully differential measurements. Well below the field-modified recollision threshold we enter the multiphoton regime. Strongly correlated back-to-back emission of the electrons along the polarization direction is observed to dominate in striking contrast to all previous data. No effect of Coulomb repulsion can be found, the predicted cutoff in the sum-energy spectra of two emitted electrons is confirmed, and the potential importance of multiple recollisions is discussed. DOI: 10.1103/PhysRevLett.101.053001 PACS numbers: 32.80.Rm, 31.90.+s, 32.80.Fb, 32.80.Wr Within the past three decades extensive studies on the interaction of intense laser fields with atoms and molecules have resulted in a profound understanding of various strong-field phenomena. Prominent examples are abovethreshold ionization (ATI) [1] or high-order harmonic generation [2], both essentially treatable within the single active electron (SAE) approximation. Correlated fewelectron processes, on the other hand, most important, for example, in nonsequential double (multiple) ionization (NSDI) (for a recent review see, e.g., [3]) have, until the present day, resisted any comprehensive modeling.Recently, however, a breakthrough was achieved at high intensities ( PW=cm 2 ) [4]. The application of many-particle imaging techniques [reaction microscopes and cold target recoil ion momentum spectroscopy (COLTRIMS)] [5] has allowed recording (multi)differential data on strong-field few-electron reactions and sophisticated calculations (see, e.g., [6] and references therein) have advanced their theoretical interpretation. As a result, a commonly accepted though simple picture has emerged, characterizing NSDI. Here an electron first tunnels into the field, is then accelerated, and finally thrown back onto its parent ion by the oscillating laser field. During ''recollision'' n-fold ionization might occur either in a direct e; ne -like encounter or indirectly via recollision-induced excitation of the ion plus subsequent field ionization (RESI) [7]. Signatures of the former are that both electrons are exclusively emitted into the same hemisphere along the polarization direction leading to ''double-hump'' shaped parallel momentum distributions of the ions (compensating the electron momenta). For RESI instead, according to the present understanding, the electrons can be emitted either parallel or back to back, thus filling the valley in between the double hump for the ions. Beyond the well-accepted simple scenario, however, major questions about the correlated electron emission are still far from being understood and are extensively investigated [6,8] because recollision is at the very heart of attoscience, molecular tomography, or imaging [9].At low intensities one intriguing though still widely unexplored question did arise early on within the above picture [10]. What happens when the energy of the recolliding electron of up to 3:17U P is not sufficient t...

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Strong-Field Double Ionization of Ar below the Recollision Threshold

et al. 2008

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“…[14]. In particular, in this reference, the distributions encountered have been modeled employing the electron-impact ionization physical mechanism and a modified ionization threshold for the second electron.…”

Section: Comparison With Experimentsmentioning

confidence: 99%

“…For the latter species, an explicit comparison with the results in Ref. [14] is performed. Finally, in Sec.…”

Section: Introductionmentioning

confidence: 99%

Laser-induced nonsequential double ionization at and above the recollision-excitation-tunneling threshold

2010

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We perform a detailed analysis of the recollision-excitation-tunneling (RESI) mechanism in laserinduced nonsequential double ionization (NSDI), in which the first electron, upon return, promotes a second electron to an excited state, from which it subsequently tunnels, based on the strong-field approximation. We show that the shapes of the electron momentum distributions carry information about the bound-state with which the first electron collides, the bound state to which the second electron is excited, and the type of electron-electron interaction. Furthermore, one may define a driving-field intensity threshold for the RESI physical mechanism. At the threshold, the kinetic energy of the first electron, upon return, is just sufficient to excite the second electron. We compute the distributions for helium and argon in the threshold and above-threshold intensity regime. In the latter case, we relate our findings to existing experiments. The electron-momentum distributions encountered are symmetric with respect to all quadrants of the plane spanned by the momentum components parallel to the laser-field polarization, instead of concentrating on only the second and fourth quadrants.

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“…This observable has allowed to disentangle the common sequential and non-sequential double RESI, rescattering impact ionization and laser-field assisted rescattering ionization mechanisms [12,13,37]. Fig.…”

Section: Correlated Two-electron Momentum Mapsmentioning

confidence: 99%

Double-Electron Ionization Driven by Inhomogeneous Fields

Chacón

Ortmann

Cucchietti

et al. 2018

Exploring the World With the Laser

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Electron-electron correlation effects play an instrumental role in our understanding of sequential (SDI) and non-sequential double ionization (NSDI) mechanisms. Here, we present a theoretical study of NSDI driven by plasmonic-enhanced spatial inhomogeneous fields. By numerically solving the time-dependent Schrödinger equation for a linear reduced model of He and a double-electron time-evolution probability analysis, we provide evidence for the enhancement effects in NSDI showing that the double ionization yield at lower laser peak intensities is increased due to the inhomogeneity of the laser field. Furthermore, our quantum mechanical model, as well as classical trajectory Monte Carlo simulations, show that inhomogeneous fields are a useful tool for splitting the binary and recoil processes in the rescattering scenario.

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Laser-induced non-sequential double ionization investigated at and below the threshold for electron impact ionization

Cited by 102 publications

References 40 publications

Strong-Field Double Ionization of Ar below the Recollision Threshold

Strong-Field Double Ionization of Ar below the Recollision Threshold

Laser-induced nonsequential double ionization at and above the recollision-excitation-tunneling threshold

Double-Electron Ionization Driven by Inhomogeneous Fields

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