Quantum enhancement in laser-assisted photoionization and a method for the measurement of an attosecond xuv pulse

Yu-Cheng, Ge

doi:10.1103/physreva.77.033851

Cited by 8 publications

(9 citation statements)

References 30 publications

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“…In the context of laser-assisted photoelectric effect, applications of the strong-field approximation have concentrated on the description of sideband intensities for long single XUV pulses [19][20][21] and on the transition to the streaking regime [22][23][24] when the XUV pulse duration is reduced below one femtosecond [25][26][27][28]. A reconstruction method for SAPs based on the strong field approximation and on measurements conducted at different intensities of the dressing laser has also been proposed [29]. Since in all these cases, the energy of the photoelectron is much larger than that of a single quantum of the dressing field, the more specialized term soft-photon approximation (SPA) [20] will be used.…”

Section: Introductionmentioning

confidence: 99%

The soft-photon approximation in infrared-laser-assisted atomic ionization by extreme-ultraviolet attosecond-pulse trains

2013

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We use the soft-photon approximation, formulated for finite pulses, to investigate the effects of the dressing pulse duration and intensity on simulated attosecond pump-probe experiments employing trains of attosecond extremeultraviolet pulses in conjunction with an IR probe pulse. We illustrate the validity of the approximation by comparing the modelled photoelectron distributions for the helium atom, in the photon energy region close to the N = 2 threshold, to the results from the direct solution of the time-dependent Schrödinger equation for two active electrons. Even in the presence of autoionizing states, the model accurately reproduces most of the background features of the ab initio photoelectron spectrum in the 1s channel. A splitting of the photoelectron harmonic signal along the polarization axis, in particular, is attributed to the finite duration of the probe pulse. Furthermore, we study the dependence of the sideband integrated signal on the pump-probe time delay for increasing IR field strengths. Starting at IR intensities of the order of ∼1 TW cm −2 , overtones in the sideband oscillations due to the exchange of three or more IR photons start to appear. We derive an analytical expression in the frequency-comb limit of the 3

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Section: Introductionmentioning

confidence: 99%

The soft-photon approximation in infrared-laser-assisted atomic ionization by extreme-ultraviolet attosecond-pulse trains

2013

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“…This is mainly because the usefulness of such attosecond pulses is limited by the degree to which they can be synthesized in the laboratory. In particular, a precise characterization of such pulses in the time domain still remains a challenging task [10][11][12][13][14][15][16][17][18][19][20][21][22].…”

Section: Introductionmentioning

confidence: 99%

Attosecond pulse characterization

Laurent¹,

Cao²,

Ben‐Itzhak³

et al. 2013

Opt. Express

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Abstract:In this work we propose a novel procedure for the characterization of attosecond pulses. The method relies on the conversion of the attosecond pulse into electron wave-packets through photoionization of atoms in the presence of a weak IR field. It allows for the unique determination of the spectral phase making up the pulses by accurately taking into account the atomic physics of the photoionization process. The phases are evaluated by optimizing the fit of a perturbation theory calculation to the experimental result. The method has been called iPROOF (improved Phase Retrieval by Omega Oscillation Filtering) as it bears a similarity to the PROOF technique [Chini et al. Opt. Express 18, 13006 (2010)]. The procedure has been demonstrated for the characterization of an attosecond pulse train composed of odd and even harmonics. We observe a large phase shift between consecutive odd and even harmonics. The resulting attosecond pulse train has a complex structure not resembling a single attosecond pulse once per IR period, which is the case for zero phase. Finally, the retrieval procedure can be applied to the characterization of single attosecond pulses as well.

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“…low intensity S L and high intensity S H , or corresponding ponderomotive potentials L P U and H P U , respectively. The spectral position W of a PES and the birth time t of a measured photoelectron satisfy the following integral equation [28] :…”

Section: Transfer Equations For Broad Bandwidth Attosecond X-ray Pulsmentioning

confidence: 99%

“…, that is quantum-mechanically calculated for a cross correlated monochromatic attosecond X-ray pulse and a Gaussian-shaped laser with duration τ L = 7 fs [28] . The duration of a Gaussian-shaped X-ray pulse is τ X = 400 as (FWHM), and the photon energy is X ϖ h =283.7 eV, where ϖ X is the X-ray angular frequency.…”

Section: Pes N(w)mentioning

confidence: 99%

Radiation properties of high-order harmonic generation for the measurements of femto- and attosecond X-ray pulses

Yu-Cheng

2009

Chin. Sci. Bull.

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REVIEW OPTICSCitation: Ge Y C. Radiation properties of high-order harmonic generation for the measurements of femto-and attosecond X-ray pulses.Radiation properties of high-order harmonic generation (HHG) are calculated for atoms in a strong laser field. The laser-duration dependence and the carrier-envelope-phase (CEP) dependence of HHG radiation properties are presented. The CEP dependence of the pure single distribution pulse of HHG radiation properties shows interesting 180° periodic structures. The quantum enhancement of the laser-assisted photo-ionization by femtosecond (1 fs=10 −15 s) and attosecond (1 as=10 −18 s) X-ray pulses and the interference patterns of photo-electron energy spectra are theoretically investigated. Transfer equations are presented for pulse reconstructions. The theoretical root-mean-square time (energy) differences of attosecond pulse reconstructions with different durations are less than 2 as (0.8 eV). These methods may be developed as basic techniques to access ultra-fast measurements and molecular movie.high-order harmonic generation, radiation properties, ultra-fast measurement, transfer equation, laser-phase determination method Electric, scanning tunneling and atomic force microscopes help scientists see interesting images of micro world on atomic scales. Ultra-fast measurement opens a door for scientists to get new knowledge. Usually, we know what happens in a chemical or biochemical reaction, but we do not know how it happens. Knowing how it happens and then regulating or manipulating it is very important for scientific researches. It is well known that the electron and energy transfers in a chemical or biochemical reaction take place on femtosecond and attosecond time scales, and that a molecular vibration period is about a hundred femtoseconds. Up to date, studying and measuring these dynamic processes have been one of the frontier topics that attract increasing attentions. Ultra-fast measurement needs increasingly shorter X-ray pulses, e.g. femto-and attosecond X-ray pulses. In the last three decades, the technique of pump-probe measurement with two delayed light pulses on picosecond time scale has been successfully used in the fast measurements of chemical reaction, biophysics and other fundamental scientific researches. Today, the techniques of synchrotron radiation, 90° Thomson scattering between high energy electrons and laser beam are used to produce femtosecond X-ray pulses. Particularly, highorder harmonic generation (HHG) is a successful way to produce attosecond X-ray pulses. These pulses can help scientists study inner atomic structure, molecular state transition and reaction dynamic process, rather than only the outer atomic structure and the final reaction productions. However, how to measure them remains a challenge.In order to better produce and use the femto-and attosecond X-ray pulses, the pulse properties such as the time distributions of the pulse intensity and frequency (chirp) have to be further studied and experimentally measured.

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Quantum enhancement in laser-assisted photoionization and a method for the measurement of an attosecond xuv pulse

Cited by 8 publications

References 30 publications

The soft-photon approximation in infrared-laser-assisted atomic ionization by extreme-ultraviolet attosecond-pulse trains

The soft-photon approximation in infrared-laser-assisted atomic ionization by extreme-ultraviolet attosecond-pulse trains

Attosecond pulse characterization

Radiation properties of high-order harmonic generation for the measurements of femto- and attosecond X-ray pulses

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