Atomic excitation during recollision-free ultrafast multi-electron tunnel ionization

Bryan, William A.; Stebbings, Sarah L.; McKenna, J. A.; English, E. M. L.; Suresh, M.; Wood, James B.; Srigengan, B.; Turcu, I. C. E.; Smith, Jonathan M.; Divall, E. J.; Hooker, C. J.; Langley, A. J.; Collier, J.; Williams, Ian D.; Newell, W R

doi:10.1038/nphys310

Cited by 90 publications

(64 citation statements)

References 29 publications

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“…The presence of low-order harmonics and substantial gas ionization already implies rather high intensities within the nanostructures [72,73,74]. (Note that the ionization energies of the gases used (argon: 15.8 eV, xenon: 12.1 eV) exceed the energy of ten and seven laser photons, respectively.)…”

Section: Methodsmentioning

confidence: 99%

Extreme-ultraviolet light generation in plasmonic nanostructures

et al. 2013

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The present (cumulative) thesis examines fundamentals of nanostructure-enhanced extreme-ultraviolet light generation in noble gases using two different nanostructure geometries for local field-enhancement. Specifically, resonant antennas and tapered hollow waveguide nanostructures are utilized to enhance low-energy femtosecond laser pulses, which in turn induce light emission from excited xenon, argon and neon atoms and ions. Spectral analysis of this radiation reveals that coherent high-order harmonic generation is not feasible under the examined conditions, contrary to former expectations and reports. Instead, the spectral characteristics unequivocally identify that incoherent fluorescence from multiphoton excited and strong-field ionized gas atoms is the predominant process in such schemes. Furthermore, novel nanostructure-enhanced effects are reported such as surface-enhanced fifth-order harmonic generation (from bow-tie nanoantennas) and the formation of a bistable nanoplasma (in a hollow waveguide). These effects offer intriguing links between nonlinear nano-optics, plasma dynamics and extreme-ultraviolet radiation.v vi

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Section: Methodsmentioning

confidence: 99%

Extreme-ultraviolet light generation in plasmonic nanostructures

et al. 2013

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“…It has been proposed that inelastic tunneling [26,27], where the first electron escapes leaving the core in an excited state, is important in double and multiple ionization at high laser intensities. However, the most typical picture of the ionization process revealed by our classical model is that the first electron ionizes leaving the second electron at the ground sate of Ar + , as shown in fig.…”

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Classical Simulations Including Electron Correlations for Sequential Double Ionization

et al. 2012

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With a classical ensemble model that including electron correlations during the whole ionization process, we investigated strong-field sequential double ionization of Ar by elliptically polarized pulses at the quantitative level. The experimentally observed intensity-dependent three-band or four-band structures in the ion momentum distributions are well reproduced with this classical model. More importantly, the experimentally measured ionization time of the second electrons [A. N. Pfeiffer et al., Nature Phys. 7, 428 (2011)], which can not be predicted by the standard independent-electron model, is quantitatively reproduced by this fully classical correlated model. The success of our work encourages classical description and interpretation of the complex multi-electron effects in strong field ionization where nonperturbative quantum approaches are currently not feasible.PACS numbers: 32.80. Rm, 31.90.+s, 32.80.Fb Among various intense laser-induced phenomena, strong field double ionization (DI) is one of the most important and fundamental processes. During the past decades, a great number of experimental as well as theoretical studies have been performed on this area. It has been known that DI proceeds either sequentially or nonsequentially. In nonsequential double ionization (NSDI), the second electron is ionized by the recollision of the first tunneled electron [1]. Because of this recollision, the two electrons from NSDI exhibit a highly correlated behavior [2][3][4][5][6]. In sequential double ionization (SDI), it is usually assumed that no correlation exists between the two electrons, and thus the ionization of the electrons can be treated as two independent tunneling-ionization steps. However, this assumption has been called into doubt by recent experiments [7,8]. In Ref. [7], it has been shown that there is a clear angular correlation between the two electrons from SDI, which implies that the successive ionization steps are not independent in SDI. In Ref.[8], the authors found that the ionization time of the second electron from SDI is much earlier than the prediction of the independent-electron model. These observations declare that the electron correlations in SDI should be reexamined carefully.Theoretically, an accurate description of the electron correlations in DI needs full quantum theory. However, due to the enormous computational demand, the solution of the time-dependent schrödinger equation of the two-electron system in the strong field, especially in the case of elliptically polarized laser fields, is not feasible currently. Instead, a fully classical treatment of the twoand multi-electron systems proposed by Eberly et al. has been well established [9][10][11][12]. During the past decade, this model has been successful in exploring the strong-field ionization processes at the qualitative level. However, * Corresponding author: lupeixiang@mail.hust.edu.cn it fails when made a quantitative comparison with experiments. For example, in ref. [13] it has been shown that the saturation intensity ...

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“…Indeed, recent work shows that elliptic polarization (EP) provides a new control mechanism for recollision physics in high-field ionization [8]. To illustrate the conceptual difficulty associated with polarization, consider circularly polarized (CP) fields: The recollision scenario which works so well in LP fields is much more difficult to justify in fields in which the ionized electrons tend to spiral out from the core and to miss it [9]. Therefore one has to come to expect any recollision in CP fields to be due to contamination by small amounts of EP fields, but not otherwise.…”

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confidence: 99%

Recollisions and Correlated Double Ionization with Circularly Polarized Light

2010

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It is generally believed that the recollision mechanism of atomic nonsequential double ionization is suppressed in circularly polarized laser fields because the returning electron is unlikely to encounter the core. On the contrary, we find that recollision can and does significantly enhance double ionization, even to the extent of forming a "knee", the signature of the nonsequential process. Using a classical model, we explain two apparently contradictory experiments, the absence of a knee for helium and its presence for magnesium.

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Atomic excitation during recollision-free ultrafast multi-electron tunnel ionization

Cited by 90 publications

References 29 publications

Extreme-ultraviolet light generation in plasmonic nanostructures

Extreme-ultraviolet light generation in plasmonic nanostructures

Classical Simulations Including Electron Correlations for Sequential Double Ionization

Recollisions and Correlated Double Ionization with Circularly Polarized Light

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