Available Equipment (ELI-ERIC)

Available Equipment (ELI-ERIC)

High Repetition rate laser system-based Gas High-order Harmonic Generation beamline for Condensed targets - HR GHHG Cond

The High Repetition rate laser system-based Gas High-order Harmonic Generation attosecond beamline for Condensed targets (HR GHHG Cond) of ELI-ALPS is driven by the 100 kHz high average-power HR-1 or HR-2 laser system and produces attosecond pulse trains (APTs) for extreme ultraviolet (XUV) – infrared (IR) pump-probe measurements on condensed-phase targets.

The beamline may be used for scientific experiments with its built-in diagnostics (e-TOF, photon spectrometer), or with dedicated endstations (e.g. NanoESCA).

Contact person

Balázs Major
(balazs.major[@]eli-alps.hu)

 

Brief description of the available set up

 

The HR GHHG Condensed attosecond, XUV-IR pump-probe beamline incorporates a time-delay compensated (TDC) monochromator to provide users with the possibility of selecting different XUV photon energy regions of the generated high-order harmonic radiation down to the 50 meV spectral bandwidth, while preserving the few (tens of) femtosecond duration of the XUV pulses. Transmission of the total available XUV spectrum (in “broadband” operation) or monochromatic pulses with longer temporal extent, but higher flux (in “high-flux” mode, HFM) is also possible [1]. The beamline is in continuous upgrade and optimisation to extend the available parameter range, the first experiments were carried out in 2022. 

Upon achieving the CEP stability of the driver lasers, isolated attosecond pulse production will be available (foreseen by the experimental period of this call).

Description of key areas of science

 

The HR GHHG Cond beamline is primarily designed to study dynamical effects on the femtosecond to attosecond timescale in solid-state targets, primarily being the subject of research in condensed state physics and chemistry or surface science. These involve studies of phase transitions [3], the analysis of laser-assisted photoelectric effect [4], or following electronic correlations and collective excitations, electron transport, transient and unoccupied states [5,6]. 

Full description of system

 

Representative parameters of the HR GHHG Cond beamline are given below:

  Available now (HR-1 short pulse mode, Ar gas, Al filter)*
Repetition rate 100 kHz
Energy stability ±50 %
Strehl ratio not available
Temporal quality not applicable
Pulse duration 170 as pulses (in 20 fs attosecond pulse train during broadband operation, down to 15 fs in monochromatic operation)
Average power 9.5 µW (3.4 μW on target)
Pulse energy (max) 95 pJ (34 pJ on target)
Pulse energy (Min-Max range) 3 - 95 pJ (1 - 34 pJ on target)
Central wavelength 30 nm (42 eV)
Spectral bandwidth 19 - 39 nm (32 - 66 eV)
Pointing stability not available
Temporal contrast (ns) not applicable
Temporal contrast (ps) not applicable
Polarization linear (p or s)
CEP stabilization not applicable
Near field intensity distribution Gaussian
Beam size not available

*Due to the high flexibility of the beamline, other parameters (spectral range, pulse duration, …) are available. Users are strongly suggested to contact the equipment responsible for availability of other specifications.

Main experimental geometries

 

The schematic layout of the HR GHHG Cond beamline can be seen in the figure below.

Recombination of the XUV and IR beams is done before “Target area 1” in section “Monochromator stage 2 & Recombination”. This allows for parallel measurements with the electron-TOF detector in “Target area 1” and in the solid-state physics end station NanoESCA. The two stages of the XUV monochromator (“Monochromator stage 1” and “Monochromator stage 2 & Recombination”) are responsible for the spectral tuning and time-compensation of the XUV radiation, thus providing femtosecond duration XUV beam with adjustable spectral parameters.

Figure 1: The schematic layout of the HR GHHG Cond beamline

Available target systems

 

Permanent target systems:

  • Electron time-of-flight (TOF) spectrometer (Stefan Kaesdorf ETF-11)

  • Solid-state physics end station (“NanoESCA”)

  • (“Target area 1” potentially available for other smaller target systems provided by the user, or alternative setup soon to be available for transmission measurements of thin solid targets.)

Available metrology

 

The following diagnostics are available as diagnostics tools and metrology in a permanent manner in the HR GHHG Cond beamline:

  • Electron TOF spectrometer (Stefan Kaesdorf ETF-11) for temporal characterisation of the XUV APTs using the RABBITT method [2]

  • XUV photodiode (NIST 40790C) for XUV energy measurements

  • XUV flat-field spectrometer (home built) for spectral characterisation


References

[1] Tamás Csizmadia, Zoltán Filus, Tímea Grósz, Peng Ye, Lénárd Gulyás Oldal, Massimo De Marco, Péter Jójárt, Imre Seres, Zsolt Bengery, Barnabás Gilicze, Matteo Lucchini, Mauro Nisoli, Fabio Frassetto, Fabio Samparisi, Luca Poletto, Katalin Varjú, Subhendu Kahaly, and Balázs Major, “Spectrally tunable ultrashort monochromatized extreme ultraviolet pulses at 100 kHz,” submitted (2023)
https://doi.org/10.48550/arXiv.2211.02955  

[2] P. Ye, L. Gulyás Oldal, T. Csizmadia, Z. Filus, T. Tímár-Grósz, P. Jójárt, I. Seres, Zs. Bengery, B. Gilicze, S. Kahaly, K. Varjú, B. Major, “High-flux 100-kHz attosecond pulse source driven by a high average power annular laser beam”, Ultrafast Science 2022, 9823783 (2022)
https://doi.org/10.34133/2022/9823783

[3] Eich et al., “Band structure evolution during the ultrafast ferromagnetic-paramagnetic phase transition in cobalt”, Sci. Adv. 3, e1602094 (2017)
https://doi.org/10.1126/sciadv.1602094  

[4] Marius Keunecke et al., “Electromagnetic dressing of the electron energy spectrum of Au(111) at high momenta”, Phys. Rev. B 102, 161403(R), (2020)
https://doi.org/10.1103/PhysRevB.102.161403  

[5] D. Garratt et al., “Direct observation of ultrafast exciton localization in an organic semi-conductor with soft x-ray transient absorption spectroscopy,” Nature Communications,13(1), 3414, (2022)
https://doi.org/10.1103/10.1038/s41467-022-31008-w

[6] D. Friedrich, P. Sippel, O. Supplie, T. Hannappel, and R. Eichberger, “Two-photon photoemission spectroscopy for studying energetics and electron dynamics at semiconductor interfaces,” physica status solidi (a) 216(8), 1 800 738, (2019)
https://doi.org/10.1002/pssa.201800738 

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