Mapping attosecond electron wave packet motion

Niikura, Hiromichi; Villeneuve, D. M.; Corkum, P. B.

doi:10.1007/3-540-27213-5_48

Cited by 5 publications

(10 citation statements)

References 15 publications

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“…Under these circumstances, the synchrony of wave-packet dynamics in the specimens of the ensemble (that is, coherence) is indispensable and only time-resolved measurements can provide direct access to the observables of the motion. Combination of the powerful concepts of correlated measurement and high-harmonic spectroscopy [6][7][8][9] has recently uncovered signatures of electronic coherence and resultant dynamics in an ensemble of ionizing molecules within a temporal window of ,1 fs following ionization 10 . The degree and the persistence of coherence have not been measured and the method is limited to the scrutiny of systems with large ($10 eV) ionization potentials and of processes under strong-field influence.…”

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confidence: 99%

Real-time observation of valence electron motion

Goulielmakis

Loh

Wirth

et al. 2010

Nature

1,154

974

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The superposition of quantum states drives motion on the atomic and subatomic scales, with the energy spacing of the states dictating the speed of the motion. In the case of electrons residing in the outer (valence) shells of atoms and molecules which are separated by electronvolt energies, this means that valence electron motion occurs on a subfemtosecond to few-femtosecond timescale (1 fs = 10(-15) s). In the absence of complete measurements, the motion can be characterized in terms of a complex quantity, the density matrix. Here we report an attosecond pump-probe measurement of the density matrix of valence electrons in atomic krypton ions. We generate the ions with a controlled few-cycle laser field and then probe them through the spectrally resolved absorption of an attosecond extreme-ultraviolet pulse, which allows us to observe in real time the subfemtosecond motion of valence electrons over a multifemtosecond time span. We are able to completely characterize the quantum mechanical electron motion and determine its degree of coherence in the specimen of the ensemble. Although the present study uses a simple, prototypical open system, attosecond transient absorption spectroscopy should be applicable to molecules and solid-state materials to reveal the elementary electron motions that control physical, chemical and biological properties and processes.

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mentioning

confidence: 99%

Real-time observation of valence electron motion

Goulielmakis

Loh

Wirth

et al. 2010

Nature

1,154

974

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“…Similar temporal resolution could also be achieved by directly using the broadband electron wavepacket. This opens up a new regime for timeresolved tomography of atomic or molecular wavefunctions 5,6 and ultrafast dynamics.During high-order harmonic generation (HHG) in gas 7 , short electron wavepackets (EWPs) are periodically released by high-field ionization. Their subsequent coherent interaction with the remaining bound wavefunction leads to coherent extremeultraviolet (XUV) emission.…”

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confidence: 99%

mentioning

confidence: 99%

Controlling attosecond electron dynamics by phase-stabilized polarization gating

et al. 2006

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A ttosecond electron wavepackets are produced when an intense laser field ionizes an atom or a molecule 1 . When the laser field drives the wavepackets back to the parent ion, they interfere with the bound wavefunction, producing coherent subfemtosecond extreme-ultraviolet light bursts. When only a single return is possible 2,3 , an isolated attosecond pulse is generated. Here we demonstrate that by modulating the polarization of a carrier-envelope phase-stabilized short laser pulse 4 , we can finely control the electron-wavepacket dynamics. We use high-order harmonic generation to probe these dynamics. Under optimized conditions, we observe the signature of a single return of the electron wavepacket over a large range of energies. This temporally confines the extreme-ultraviolet emission to an isolated attosecond pulse with a broad and tunable bandwidth. Our approach is very general, and extends the bandwidth of attosecond isolated pulses in such a way that pulses of a few attoseconds seem achievable. Similar temporal resolution could also be achieved by directly using the broadband electron wavepacket. This opens up a new regime for timeresolved tomography of atomic or molecular wavefunctions 5,6 and ultrafast dynamics.During high-order harmonic generation (HHG) in gas 7 , short electron wavepackets (EWPs) are periodically released by high-field ionization. Their subsequent coherent interaction with the remaining bound wavefunction leads to coherent extremeultraviolet (XUV) emission. The T 0 /2 periodicity of this process (T 0 being the laser optical period) ensures that only odd harmonics of the fundamental radiation are emitted. Temporally, the XUV pulses are emitted as a train of chirped attosecond pulses [8][9][10] (1 attosecond = 10 −18 s). For both plateau (low energy) and cut-off (high energy) harmonics, specific focusing conditions ensure that only a single attosecond pulse is emitted every half cycle 11,12 . Extracting an isolated attosecond pulse from this train requires breaking the periodicity of the process, so that XUV emission is only possible within a single half cycle of the fundamental pulse. In this way, isolated 250-attosecond-long Figure 1 Spectra generated in argon. Spectra emitted from an argon medium irradiated with a polarization-modulated pulse (τ = 5 fs, δ = 6.2 fs, β = 0 • ) as a function of the CEP shift. For some CEPs, harmonic peaks appear, whereas for other CEPs, they broaden up to a continuum.pulses were recently obtained 13 by selecting the (highly intensity dependent) cut-off harmonics generated in neon by a 5-fs linearly polarized, fundamental pulse with stabilized carrierenvelope phase (CEP). With this technique, the minimum pulse duration achievable is limited by the (∼10 eV) bandwidth of the selected cut-off harmonics, which prevents us reaching the sub-100-attosecond domain.To isolate a broadband attosecond pulse, we used a different approach 2 . Our approach relies on the strong HHG sensitivity on the ellipticity, ε, of the fundamental field, which is largely nature phy...

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“…The total efficiencies of the monochromator are reported in Tab. [4][5][6][7]. The values at the blaze wavelength of each grating are in the 0.21-0.28 interval.…”

Section: Efficiencymentioning

confidence: 99%

“…The HH spectrum is described as a sequence of peaks corresponding to the odd harmonics of the fundamental laser wavelength and having an intensity distribution characterized by a vast plateau whose extension is related to the pulse intensity. The radiation generated with the scheme of the HHs generated by laser pulses of a few optical cycles recently become the tool for the investigation of matter with sub-femtosecond, or l4ra[carrier envelope phase (CEP) stable laser system Hollow fibre essor Target B roa d band a n d/or monochromaticXuV attosecond, resolution (1 as = 10 -18 s) [2][3][4][5]. The access to this unexplored time domain opens new frontiers in atomic, molecular and solid-state science [6], as it becomes possible to do experiments with an unprecedented time resolution and intensity.…”

Section: Introductionmentioning

confidence: 99%

Design and characterization of the XUV monochromator for ultrashort pulses at the ARTEMIS facility

et al. 2008

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ARTEMIS, a multi-partner and multidisciplinary project, will be a users-dedicated facility that will provide ultrashort XUV pulses through high harmonic generation in a gas target. This high repetition rate synchronized source will allow new science in research fields spanning from the material science to the molecular physics and chemistry. The XUV radiation is expected to cover the range 10 -100 nm with an estimated photons flux up to 10 11 photons/s per harmonic. In this work we present the design and characterization of the monochromator that will be used in the beamline for the experiments requiring wavelength and bandwidth selection. The working principle is based on a plane grating operated at grazing incidence in the off-plane mount. This geometry has been selected because of the high diffraction efficiency, expected to be about 30%. To cover the entire spectral range four gratings can be selected which span over different regions and with different spectral resolution. When the appropriate grating is chosen, the wavelength scanning is performed by rotating the grating around an axis passing through the grating center and parallel to the grooves direction. The off-plane mount requires the grating to be used in collimated light, consequently the optical scheme is completed by two toroidal mirrors, the first in front of the source that collimates the XUV radiation before the grating and the second after the grating to focalize the spectrally dispersed photons on the exit slit. Using a single grating, the configuration is not time-delay-compensated, nevertheless the time broadening (depending on the source divergence, the wavelength, and the grating) is less than 50 fs.

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Mapping attosecond electron wave packet motion

Cited by 5 publications

References 15 publications

Real-time observation of valence electron motion

Real-time observation of valence electron motion

Controlling attosecond electron dynamics by phase-stabilized polarization gating

Design and characterization of the XUV monochromator for ultrashort pulses at the ARTEMIS facility

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