Ionization of helium by a short pulse of radiation: A Fermi molecular-dynamics calculation

Lerner, P. B.; LaGattuta, K. J.; Cohen, James S.

doi:10.1103/physreva.49.r12

Cited by 349 publications

(27 citation statements)

References 14 publications

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“…Finally, we note that in recent classical trajectory studies for a model helium atom [16], the intensity dependence of the He+ yield has two components which can be interpreted to show the existence of two separate rates, one for sequential ionization and the second for direct double ionization. This is at least qualitatively consistent with the experimental data.…”

Section: Discussionmentioning

confidence: 75%

Laser-assisted inelastic rescattering during above-threshold ionization

1995

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As an electron is freed from an atom by an intense laser it is accelerated by the oscillating field. Before escaping entirely, it may recollide with its parent ion. During this rescattering, the remaining electrons of the ion might be excited or ionized. The influence of the laser field on these impact excitation and ionization processes is investigated. Model calculations for helium at 780 nm and intensities near 10" W/cm show that the effect of the field on the total probability of promoting an electron from the ionic ground state is small. However, the laser alters the final excited-state populations, rapidly ionizing any excited bound states. We discuss the importance of these results in the search for the mechanism responsible for direct double ionization in the tunneling regime.PACS number(s): 32.80.Rm

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Section: Discussionmentioning

confidence: 75%

Laser-assisted inelastic rescattering during above-threshold ionization

1995

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“…In contrast to MPI, the efficiency of Zener tunneling is expected to be similar for linearly polarized (LP) and circularly polarized (CP) light (20)(21)(22)(23)(24). We note that in gasses, theories variably predict modest reduction of the efficiency of Zener tunneling for CP versus LP light (22)(23)(24).…”

Section: To Differentiate Between Mpi and Zener Tunneling Of Electronmentioning

confidence: 99%

Optics at critical intensity: Applications to nanomorphing

Joglekar

Liu

Meyhöfer

et al. 2004

Proc. Natl. Acad. Sci. U.S.A.

251

169

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Laser-induced optical breakdown by femtosecond pulses is extraordinarily precise when the energy is near threshold. Despite numerous applications, the basis for this deterministic nature has not been determined. We present experiments that shed light on the basic mechanisms of light-matter interactions in this regime, which we term ''optics at critical intensity.'' We find that the remarkably sharp threshold for laser-induced material damage enables the structure or properties of materials to be modified with nanometer precision. Through detailed study of the minimum ablation size and the effects of polarization, we propose a fundamental framework for describing light-matter interactions in this regime. In surprising contrast to accepted damage theory, multiphoton ionization does not play a significant role. Our results also reject the use of the Keldysh parameter in predicting the role of multiphoton effects. We find that the dominant mechanism is Zener ionization followed by a combination of Zener and Zenerseeded avalanche ionization. We predict that the minimum feature size ultimately depends on the valence electron density, which is sufficiently high and uniform, to confer deterministic behavior on the damage threshold even at the nanoscale. This behavior enables nanomachining with high precision, which we demonstrate by machining highly reproducible nanometer-sized holes and grooves in dielectrics.

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“…However, this deficiency can be avoided with the Heisenberg-core potential, which not only prevents autoionization but also gives the ground-configuration energies of the multi-electron atoms [19]. In the past decades, this potential has been extensively employed in the classical investigations of atomic and molecular collisions and laser-matter interactions [20,21]. Here, we employ the Heisenberg-core potential instead of the soft-core potential in the classical two-electron model to study SDI of Ar by the elliptical laser pulses.…”

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confidence: 99%

“…For the two-electron atom, in refs. [19][20][21], the ground-state energy of the system is obtained by minimizing the Hamiltonian H 0 . In that configuration, the two electrons locate at opposite sides of the nucleus, and they are stationary to each other [19].…”

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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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Ionization of helium by a short pulse of radiation: A Fermi molecular-dynamics calculation

Cited by 349 publications

References 14 publications

Laser-assisted inelastic rescattering during above-threshold ionization

Laser-assisted inelastic rescattering during above-threshold ionization

Optics at critical intensity: Applications to nanomorphing

Classical Simulations Including Electron Correlations for Sequential Double Ionization

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