Efficient and tunable high-order harmonic light sources for photoelectron spectroscopy at surfaces

Chiang, Cheng‐Tien; Huth, Michael; Trützschler, Andreas; Schumann, F. O.; Kirschner, J.; Widdra, W.

doi:10.1016/j.elspec.2015.04.001

Cited by 18 publications

(10 citation statements)

References 45 publications

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“…When pumped with a Yb-doped fiber oscillator–amplifier laser system, which produces ∼1.03 μm femtosecond light pulses at up to several MHz repetition rates, the NOPA output is sufficiently intense to excite mPP as well as above threshold photoemission. ,, In the NOPA systems, a small portion of the IR pump pulses with 200–300 fs pulse duration generates a white light continuum, while the rest is frequency doubled and tripled to serve as pump light in one or two NOPA lines that amplify selected portions of the white light continuum. − This approach, based on a Clark MXR Inc. Yb-doped fiber oscillator–amplifier laser system and other similar lasers, produces nearly continuously tunable excitation light pulses in the wavelength range of 270–900 nm ( ℏω = 4.6–1.38 eV) with achieved pulse durations as short as ∼15 fs and energies as large as 1 μJ/pulse . With effort, the pulse duration can be further decreased to <10 fs range. , The IR fiber laser pulses can also be converted in atomic gases to generate directly high harmonics in the VUV range . The broad tunability, short pulse duration, high power, and high repetition rates make the Yb-doped fiber laser pumped NOPA systems particularly well suited to study a broad spectrum of plasmonic phenomena in a variety of materials by ITR-mPP and ITR-PEEM methods. ,,,,,, …”

Section: Imaging Plasmons With Peemmentioning

confidence: 99%

“…314,316 The IR fiber laser pulses can also be converted in atomic gases to generate directly high harmonics in the VUV range. 317 The broad tunability, short pulse duration, high power, and high repetition rates make the Yb-doped fiber laser pumped NOPA systems particularly well suited to study a broad spectrum of plasmonic phenomena in a variety of materials by ITR-mPP and ITR-PEEM methods. 53,78,118,236,242,318,319 The advantage of PEEM is its ability to image the ultrafast dynamics of plasmons by recording ITR-PEEM movies.…”

Section: Tr-peem Apparatusmentioning

confidence: 99%

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Ultrafast Photoemission Electron Microscopy: Imaging Plasmons in Space and Time

2020

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Plasmonics is a rapidly growing field spanning research and applications across chemistry, physics, optics, energy harvesting, and medicine. Ultrafast photoemission electron microscopy (PEEM) has demonstrated unprecedented power in the characterization of surface plasmons and other electronic excitations, as it uniquely combines the requisite spatial and temporal resolution, making it ideally suited for 3D space and time coherent imaging of the dynamical plasmonic phenomena on the nanofemto scale. The ability to visualize plasmonic fields evolving at the local speed of light on subwavelength scale with optical phase resolution illuminates old phenomena and opens new directions for growth of plasmonics research. In this review, we guide the reader thorough experimental description of PEEM as a characterization tool for both surface plasmon polaritons and localized plasmons and summarize the exciting progress it has opened by the ultrafast imaging of plasmonic phenomena on the nanofemto scale.

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Section: Imaging Plasmons With Peemmentioning

confidence: 99%

Section: Tr-peem Apparatusmentioning

confidence: 99%

Ultrafast Photoemission Electron Microscopy: Imaging Plasmons in Space and Time

2020

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“…A longer focal length could not be tested in the setup due to geometrical constrains, nonetheless, it is expected that a higher XUV radiant power would be possible, using the present driver laser and krypton as gas medium. Due to the scarcity and higher cost of this gas, a gas recycling system 14,78 is needed for a high pressure nozzle, complicating its adoption in the current setup. Overall, the source's flux using Ar exceeds 10 11 ph/s at 21.7 eV and at 500 kHz, which is well suited for trARPES experiments 35 .…”

Section: E Comparison Between Different Nozzles and Noble Gasesmentioning

confidence: 99%

Time- and angle-resolved photoemission spectroscopy of solids in the extreme ultraviolet at 500 kHz repetition rate

Puppin

Deng

Nicholson

et al. 2019

Review of Scientific Instruments

114

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Time-and angle-resolved photoemission spectroscopy (trARPES) employing a 500 kHz extreme-ultraviolet (XUV) light source operating at 21.7 eV probe photon energy is reported. Based on a high-power ytterbium laser, optical parametric chirped pulse amplification (OPCPA), and ultraviolet-driven high-harmonic generation, the light source produces an isolated high-harmonic with 110 meV bandwidth and a flux of more than 10 11 photons/second on the sample. Combined with a stateof-the-art ARPES chamber, this table-top experiment allows high-repetition rate pump-probe experiments of electron dynamics in occupied and normally unoccupied (excited) states in the entire Brillouin zone and with a temporal system response function below 40 fs. function A(k,ω) and a matrix element between the initial and final state |M k if | 2 ; here k and ω denote the electron's wavevector and angular frequency, respectively. Many-body effects are encoded in the spectral function A(k,ω) and manifest themselves in renormalization of the bare electronic bands and in the observed lineshape 1 . In a trARPES experiment, the distribution I(k,ω) is collected for a series of delays (τ ) between pump and probe pulses: after perturbation, the population distribution f(k,ω,τ ) evolves towards a quasi-thermal distribution and energetically relaxes on femto-to picosecond timescales 2 . During relaxation, the concomitant many-body interactions affect the transient spectral function A(k,ω,τ ) and even the photoemission matrix elements might change, if the final state's orbital symmetry is altered 3 . trARPES accesses at once the population dynamics, the evolution of the spectral function and the evolution of matrix elements. trARPES has found increasingly successful applications in the past few decades 4-6 : among many examples, trARPES was used to study photo-induced phase transitions 7-11 and to observe electronic states above the Fermi level, unoccupied under equilibrium conditions [12][13][14][15][16] . Energy conservation in the photoemission processes imposes that a femtosecond light source for trARPES must possess a photon energy ω ph exceeding the work function Φ, which in most materials lies in the range between 4 to 6 eV. Ultraviolet femtosecond light sources are thus required for these experiments.The conservation of the electrons' in-plane momentum ( k ) in the photoemission process allows reciprocal space resolution. The advantage of a probe with high photon energy is Journal of Electron Spectroscopy and Related Phenomena 200, 15 (2015). 79 SPECS Surface Nano Analysis GmbH, product spectrometer PHOIBOS TM 150 (2013), see

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“…20,21 Subsequently femtosecond XUV trARPES with significant improvements in signal averaging was demonstrated by increasing the repetition rate to 1-10 kHz and employing 2D hemispherical electron analyzers for parallel angular detection of electronic dynamics in quantum materials, 12,13,[22][23][24][25][26] More recently, XUV trARPES was extended to high repetition rates of several 100 kHz and, via intra-cavity HHG, up to ultrahigh repetition rates of 100 MHz. 15,[27][28][29][30][31] Sensitive trARPES studies of low-energy electronic dynamics in quantum materials requires that high photon flux and high energy resolution are obtained simultaneously. This is possible, however, only at high repetition rates where the photoelectrons are spread out over many pulses to avoid space charge induced broadening and energy shifts.…”

Section: Introductionmentioning

confidence: 99%

A setup for extreme-ultraviolet ultrafast angle-resolved photoelectron spectroscopy at 50-kHz repetition rate

Buß

Wang

et al. 2019

Review of Scientific Instruments

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Time-and angle-resolved photoelectron spectroscopy (trARPES) is a powerful method to track the ultrafast dynamics of quasiparticles and electronic bands in energy and momentum space. We present a setup for trARPES with 22.3 eV extreme-ultraviolet (XUV) femtosecond pulses at 50-kHz repetition rate, which enables fast data acquisition and access to dynamics across momentum space with high sensitivity. The design and operation of the XUV beamline, pump-probe setup, and UHV endstation are described in detail. By characterizing the effect of space-charge broadening, we determine an ultimate source-limited energy resolution of 60 meV, with typically 80-100 meV obtained at 1-2×10 10 photons/s probe flux on the sample. The instrument capabilities are demonstrated via both equilibrium and time-resolved ARPES studies of transition-metal dichalcogenides. The 50-kHz repetition rate enables sensitive measurements of quasiparticles at low excitation fluences in semiconducting MoSe 2 , with an instrumental time resolution of 65 fs. Moreover, photo-induced phase transitions can be driven with the available pump fluence, as shown by charge density wave melting in 1T-TiSe 2 . The high repetition-rate setup thus provides a versatile platform for sensitive XUV trARPES, from quenching of electronic phases down to the perturbative limit.

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Efficient and tunable high-order harmonic light sources for photoelectron spectroscopy at surfaces

Cited by 18 publications

References 45 publications

Ultrafast Photoemission Electron Microscopy: Imaging Plasmons in Space and Time

Ultrafast Photoemission Electron Microscopy: Imaging Plasmons in Space and Time

Time- and angle-resolved photoemission spectroscopy of solids in the extreme ultraviolet at 500 kHz repetition rate

A setup for extreme-ultraviolet ultrafast angle-resolved photoelectron spectroscopy at 50-kHz repetition rate

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