Versatile attosecond beamline in a two-foci configuration for simultaneous time-resolved measurements

Locher, Reto; Lucchini, Matteo; Herrmann, J.; Sabbar, Mazyar; Weger, Matthias; Ludwig, André; Castiglioni, Luca; Greif, Michael; Hengsberger, Matthias; Gallmann, L.; Keller, U.

doi:10.1063/1.4862656

Cited by 63 publications

(49 citation statements)

References 46 publications

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“…We are able to extract the absolute two-photon, two-color photoemission delays specific to the solid target by calibrating the data against an independent atomic gas-phase reference in a two-foci experimental arrangement [10,[18][19][20] [see Fig. 1(a)].…”

Section: Absolute Two-photon Two-color Photoemission Delay Measuremementioning

confidence: 99%

“…We studied the energy-dependent electron escape time from a Cu(111) surface using an implementation of time-and angleresolved photoemission spectroscopy (tr-ARPES) with attosecond resolution [10,18,19] [ Fig. 1(a)].…”

Section: Absolute Two-photon Two-color Photoemission Delay Measuremementioning

confidence: 99%

“…The question about the correct escape velocity of the electrons and whether their dynamics are controlled by the periodic crystal potential on such small time and length scales has been debated [11,14,[15][16][17], and mainly free-electron-like propagation was observed or deduced. Kinetic-energy-resolved measurements of the time delay from valence-band excitation, with reference to a gas target [18], led to observed delays that could not be fully explained by the free-electron escape velocity. However, a conclusive proof that the effective mass has become relevant in the electron transport could not be provided.…”

Section: Introductionmentioning

confidence: 99%

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Effective mass effect in attosecond electron transport

Kasmi¹,

Lucchini²,

Castiglioni³

et al. 2017

Optica

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The electronic band structure governs the electron dynamics in solids. It defines a group velocity and an effective mass of the electronic wave packet. Recent experimental and theoretical studies suggest that an electron acquires the effective mass of its excited state over distances much larger than the lattice period of the solid. Therefore, electron propagation on atomic length scales was typically considered to be free-electron-like. Here, we test this hypothesis by probing attosecond photoemission from a Cu(111) surface. We use attosecond pulse trains in the extreme-ultraviolet (21-33 eV) to excite electrons from two initial bands within the 3d-valence band of copper. We timed their arrival at the crystal surface with a probing femtosecond infrared pulse, and found an upper limit of 350±40 as (1 as=10−18 s) for the propagation time an electron requires to assume the effective mass of its excited state. This observation implies that a final-state Bloch wave packet forms within a travel distance of 5-7 Å, which is at most two atomic layers. Using well-established theory, our measurements demonstrate the importance of the band structure even for atomic-scale electron transport. The electronic band structure governs the electron dynamics in solids. It defines a group velocity and an effective mass of the electronic wave packet. Recent experimental and theoretical studies suggest that an electron acquires the effective mass of its excited state over distances much larger than the lattice period of the solid. Therefore, electron propagation on atomic length scales was typically considered to be free-electron-like. Here, we test this hypothesis by probing attosecond photoemission from a Cu(111) surface. We use attosecond pulse trains in the extremeultraviolet (21-33 eV) to excite electrons from two initial bands within the 3d-valence band of copper. We timed their arrival at the crystal surface with a probing femtosecond infrared pulse, and found an upper limit of 350 40 as (1 as 10 −18 s) for the propagation time an electron requires to assume the effective mass of its excited state. This observation implies that a final-state Bloch wave packet forms within a travel distance of 5-7 Å, which is at most two atomic layers. Using well-established theory, our measurements demonstrate the importance of the band structure even for atomic-scale electron transport.

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Section: Absolute Two-photon Two-color Photoemission Delay Measuremementioning

confidence: 99%

Section: Absolute Two-photon Two-color Photoemission Delay Measuremementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Effective mass effect in attosecond electron transport

Kasmi¹,

Lucchini²,

Castiglioni³

et al. 2017

Optica

View full text Add to dashboard Cite

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“…The time factor is also important when light sources, such as complex laser systems [20], have a limited stability over time.…”

Section: Discussionmentioning

confidence: 99%

Acquisition of photoelectron diffraction patterns with a two-dimensional wide-angle electron analyzer

Greif

Castiglioni

Becker‐Koch

et al. 2014

Journal of Electron Spectroscopy and Related Phenomena

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An efficient and fast way to measure photoelectron diffraction data over the full 2 angular range with high data point density is presented, taking advantage of the massive parallel detection capabilities of modern two-dimensional electron detectors. We introduce generic routines for data binning and for the mapping of the detector signal onto emission angles. X-ray photoelectron diffraction patterns taken from Bi(1 1 1) with the new detection scheme are compared to data sets taken with a conventional hemispherical analyzer equipped with a channeltron detector. As a result, the data acquisition time can be reduced by roughly a factor of ten while obtaining comparable if not superior data quality. The sampling technique is extended to UV-excited angle-resolved photoelectron spectroscopy as illustrated by a mapping of the Fermi surface of Cu (1 1 1 AbstractAn efficient and fast way to measure photoelectron diffraction data over the full 2π angular range with high data point density is presented, taking advantage of the massive parallel detection capabilities of modern two-dimensional electron detectors. We introduce generic routines for data binning and for the mapping of the detector signal onto emission angles. X-ray photoelectron diffraction patterns taken from Bi(111) with the new detection scheme are compared to data sets taken with a conventional hemispherical analyzer equipped with a channeltron detector. As a result, the data acquisition time can be reduced by roughly a factor of ten while obtaining comparable if not superior data quality.The sampling technique is extended to uv-excited angle-resolved photoelectron spectroscopy as illustrated by a mapping of the Fermi surface of Cu(111).

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“…In order to perform time-resolved experiments the liquid-jet spectrometer has to be connected to a pumpprobe setup 33,34 . The actively-stabilized beamline part is shown in Fig.…”

Section: Attosecond Beamlinementioning

confidence: 99%

Photoelectron spectrometer for attosecond spectroscopy of liquids and gases

Jordan

Huppert

Brown

et al. 2015

Review of Scientific Instruments

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A new apparatus for attosecond time-resolved photoelectron spectroscopy of liquids and gases is described. It combines a liquid microjet source with a magnetic-bottle photoelectron spectrometer and an activelystabilized attosecond beamline. The photoelectron spectrometer permits venting and pumping of the interaction chamber without affecting the low pressure in the flight tube. This pressure separation has been realized through a sliding skimmer plate, which effectively seals the flight tube in its closed position and functions as a differential pumping stage in its open position. A high-harmonic photon spectrometer, attached to the photoelectron spectrometer exit port is used to acquire photon spectra for calibration purposes. Attosecond pulse trains have been used to record photoelectron spectra of noble gases, water in the gas and liquid states as well as solvated species. RABBIT scans demonstrate the attosecond resolution of this setup.

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Versatile attosecond beamline in a two-foci configuration for simultaneous time-resolved measurements

Cited by 63 publications

References 46 publications

Effective mass effect in attosecond electron transport

Effective mass effect in attosecond electron transport

Acquisition of photoelectron diffraction patterns with a two-dimensional wide-angle electron analyzer

Photoelectron spectrometer for attosecond spectroscopy of liquids and gases

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