Multiphoton ionization of atomic hydrogen in intense subpicosecond laser pulses

Rottke, H.; Wolff, B.; Brickwedde, M.; Feldmann, D.; Welge, K. H.

doi:10.1103/physrevlett.64.404

Cited by 87 publications

(26 citation statements)

References 16 publications

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“…They were first observed in MPI of xenon by subpicosecond laser pulses by Freeman and co-workers [6]. Similar structures were subsequently found in MPI of helium [7] and atomic hydrogen [8]. These experiments revealed the important role resonance enhancement plays in photoionization of atoms in a strong optical (medium wavelength) radiation field.…”

Section: Introductionmentioning

confidence: 52%

“…Their kinetic energy is thus changed only slightly by ponderomotive acceleration. We therefore measure the kinetic energy E&~, "(I) which the photoelectrons have in the laser beam when they are released from the atom [6,8,11]. Typically, the spectrum would consist of groups of narrow peaks repeated at energy intervals Ru, corresponding to photoelectrons preferentially ejected at intensities where the ionization process is enhanced by a Stark-shift-induced intermediate-state resonance.…”

Section: Introductionmentioning

confidence: 99%

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Atomic hydrogen in a strong optical radiation field

et al. 1994

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Experimental energy spectra and energy-resolved angular distributions of photoelectrons produced by multiphoton ionization of atomic hydrogen are presented for several wavelengths between 596 and 630 nm, peak intensities of about 10 W/cm, and laser pulse durations of about 0.5 ps.Resonant ionization processes via ac Stark-shift-induced resonances with excited states dominate the spectra. The results of Sturmian-Floquet calculations of these spectra and angular distributions are presented; they are in fair agreement with the experimental data.PACS number(s): 32.80.Rm, 42.50.Hz

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Section: Introductionmentioning

confidence: 52%

Section: Introductionmentioning

confidence: 99%

Atomic hydrogen in a strong optical radiation field

et al. 1994

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“…The corresponding calculation in coordinate space will be quite hard. Case IV simulates an experimental data [18]. The pulse duration is in sub-picosecond range.…”

Section: Resultsmentioning

confidence: 98%

“…Finally in Fig. 4 we show the ATI spectrum of the hydrogen atom under a pulse of 200 optical cycles (405 fs) to compare with the experimental results [18]. Since the experimental parameters usually cannot be unlimited precise, the direct comparison between experimental and theoretical results are not straightforward.…”

Section: Resultsmentioning

confidence: 99%

Calculation of atomic hydrogen and its photoelectron spectra in momentum space

Jiang

2008

Computer Physics Communications

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“…This study does not include effects from the spatial variation of the laser pulse which would be important in order to make contact with experiment [9,13,22]. From our ATI-spectra it is clear, however, that much has still to be learned about these in ultra-short pulse situations and that experimental investigations should focus on the question of the broadening of ATI-peaks due to various effects.…”

Section: A~ (T) O)e 0 (T) Cos Co (T --Z/c)mentioning

confidence: 88%

Magnetic field effects in high-frequency photoionization by intense laser pulses

Horbatsch

1993

Z Phys D - Atoms, Molecules and Clusters

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Abstract. Effects of order v/c in the description of intense high-frequency laser pulses for above-threshold-ionization (ATI) of hydrogen atoms are included in the numerical integration of the time-dependent Schr6dinger equation. The magnetic field gives rise to a motion of the electron cloud along the propagation direction of the laser pulse. It is shown that this effect does not invalidate the recent findings of stabilization against photoionization, but modifies significantly the ATI spectra. The ATI spectrum becomes simpler again as the peak laser field reaches ulta-intense values. PACS: 32.80.FkThe suppression of ionization in strong laser pulses has recently become an area of intense research. Such stability was found in one-dimensional models [1, 2], real hydrogen studies in the electric dipole approximation [3][4][5][6] and the mechanism was found to be particularly effective for excited states [7]. Recent studies focus also on the question of ATI spectra [5,6,8]. The study of atomic hydrogen in laser pulses is of great interest due to the absence of many-electron effects. Another motivation is the measurement of photoionization in hydrogen [9] which appears to rule out some versions of a widely used model of photoionization.These studies do not include the effects that arise from the magnetic field carried by the laser pulse even though this should be important as the Lorentz force moves the electron cloud away from the Coulomb center [10]. An exception is given by a semiclassical study [11] in which an ensemble of classical relativistic trajectories is used to calculate the time evolution of a (h = 0)-Wigner function. This study shows already that the stability against decay is not inhibited by the propagation along the pulse direction. It cannot, however, make correct statements * Permanent address: Physics Department, York University, Toronto, M3J 1P3, Canada about the electron spectra as it does not contain any phase information.We have made recently studies of ATI spectra for hydrogen exposed to intense laser pulses in the electric dipole approximation for photon energies where twophoton [5] and single-photon ionization [6] represent the dominant channels. The non-resonant high-frequency case is particularly interesting as the electron spectra are simple to interpret. In addition to the expected ATI-series out of the unshifted hydrogenic ground state we have observed weak peaks out of the AC stark shifted states. The appearance of such peaks was speculated upon on the basis of a high-frequency Floquet theory [12]. Our results in [6] show a broadening of the ATI peaks due to the finite interaction time during which the decay occurs (which is much shorter than the laser pulse and happens as the pulse intensity rises), but also a strong enhancement of the higher ATI peaks during the peak of the field. The additional peaks out of the Stark-shifted states are not present before the peak of the pulse is reached. The present investigation serves to find out how the strong field effects are modified as the...

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Multiphoton ionization of atomic hydrogen in intense subpicosecond laser pulses

Cited by 87 publications

References 16 publications

Atomic hydrogen in a strong optical radiation field

Atomic hydrogen in a strong optical radiation field

Calculation of atomic hydrogen and its photoelectron spectra in momentum space

Magnetic field effects in high-frequency photoionization by intense laser pulses

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