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Ultrafast recovery dynamics of dimer stripes in IrTe2
Authors:
M. Rumo,
G. Kremer,
M. Heber,
N. Wind,
C. W. Nicholson,
K. Y. Ma,
G. Brenner,
F. Pressacco,
M. Scholz,
K. Rossnagel,
F. O. von Rohr,
D. Kutnyakhov,
C. Monney
Abstract:
The transition metal dichalcogenide IrTe2 displays a remarkable series of first-order phase transitions below room temperature, involving lattice displacements as large as 20 percents of the initial bond length. This is nowadays understood as the result of strong electron-phonon coupling leading to the formation of local multicentre dimers that arrange themselves into one-dimensional stripes. In t…
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The transition metal dichalcogenide IrTe2 displays a remarkable series of first-order phase transitions below room temperature, involving lattice displacements as large as 20 percents of the initial bond length. This is nowadays understood as the result of strong electron-phonon coupling leading to the formation of local multicentre dimers that arrange themselves into one-dimensional stripes. In this work, we study the out-of-equilibrium dynamics of these dimers and track the time evolution of their population following an infrared photoexcitation using free-electron lased-based time-resolved X-ray photoemission spectroscopy. First, we observe that the dissolution of dimers is driven by the transfer of energy from the electronic subsystem to the lattice subsystem, in agreement with previous studies. Second, we observe a surprisingly fast relaxation of the dimer population on the timescale of a few picoseconds. By comparing our results to published ultrafast electron diffraction and angle-resolved photoemission spectroscopy data, we reveal that the long-range order needs tens of picoseconds to recover, while the local dimer distortion recovers on a short timescale of a few picoseconds.
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Submitted 28 October, 2025;
originally announced October 2025.
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Anomalous 4$f$ fine structure in TmSe$_{1-x}$Te$_x$ across the metal-insulator transition
Authors:
C. -H. Min,
S. Müller,
W. J. Choi,
L. Dudy,
V. Zabolotny,
M. Heber,
J. D. Denlinger,
C. -J. Kang,
M. Kalläne,
N. Wind,
M. Scholz,
T. L. Lee,
C. Schlueter,
A. Gloskovskii,
E. D. L. Rienks,
V. Hinkov,
H. Bentmann,
Y. S. Kwon,
F. Reinert,
K. Rossnagel
Abstract:
Hybridization between localized 4$f$ and itinerant 5$d$6$s$ states in heavy fermion compounds is a well-studied phenomenon and commonly captured by the paradigmatic Anderson model. However, the investigation of additional electronic interactions, beyond the standard Anderson model, has been limited, despite their predicted important role in the exotic quasiparticle formation in mixed-valence syste…
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Hybridization between localized 4$f$ and itinerant 5$d$6$s$ states in heavy fermion compounds is a well-studied phenomenon and commonly captured by the paradigmatic Anderson model. However, the investigation of additional electronic interactions, beyond the standard Anderson model, has been limited, despite their predicted important role in the exotic quasiparticle formation in mixed-valence systems. We investigate the 4$f$ states in TmSe$_{1-x}$Te$_x$ throughout a semimetal-insulator phase transition, which drastically varies the interactions related to the 4$f$ states. Using synchrotron-based hard x-ray and extreme ultraviolet photoemission spectroscopy, we resolve subtle peak splitting in the 4$f$ peaks near the Fermi level in the mixed-valent semimetal phase. The separation is enhanced by several tens of meV by increasing the lattice parameter by a few percent. Our results elucidate the evolving nature of the 4$f$ state across the phase transition, and provide direct experimental evidence for electronic interactions beyond the standard Anderson model in mixed-valence systems.
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Submitted 4 June, 2024;
originally announced June 2024.
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Multi-Mode Front Lens for Momentum Microscopy: Part II Experiments
Authors:
O. Tkach,
S. Fragkos,
Q. Nguyen,
S. Chernov,
M. Scholz,
N. Wind,
S. Babenkov,
O. Fedchenko,
Y. Lytvynenko,
D. Zimmer,
A. Hloskovskii,
D. Kutnyakhov,
F. Pressacco,
J. Dilling,
L. Bruckmeier,
M. Heber,
F. Scholz,
J. Sobota,
J. Koralek,
N. Sirica,
M. Kallmayer,
M. Hoesch,
C. Schlueter,
L. V. Odnodvorets,
Y. Mairesse
, et al. (4 additional authors not shown)
Abstract:
We have experimentally demonstrated different operating modes for the front lenses of the momentum microscopes described in Part I. Measurements at energies from vacuum UV at a high-harmonic generation (HHG)-based source to the soft and hard X-ray range at a synchrotron facility validated the results of theoretical ray-tracing calculations. The key element is a ring electrode concentric with the e…
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We have experimentally demonstrated different operating modes for the front lenses of the momentum microscopes described in Part I. Measurements at energies from vacuum UV at a high-harmonic generation (HHG)-based source to the soft and hard X-ray range at a synchrotron facility validated the results of theoretical ray-tracing calculations. The key element is a ring electrode concentric with the extractor electrode, which can tailor the field in the gap. First, the gap-lens-assisted extractor mode reduces the field strength at the sample while mitigating image aberrations. This mode gave good results in all spectral ranges. Secondly, by compensating the field at the sample surface with a negative voltage at the ring electrode we can operate in zero-field mode, which is beneficial for operando experiments. Finally, higher negative voltages establish the repeller mode, which removes all slow electrons below a certain kinetic energy to eliminate the primary contribution to the space-charge interaction in pump-probe experiments. The switch from extractor to repeller mode is associated with a reduction in the k-field-of-view (10-20 % at hard-X-ray energies, increasing to ~50% at low energies). Real-space imaging also benefits from the new lens modes as confirmed by ToF-XPEEM imaging with 650 nm resolution.
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Submitted 19 January, 2024; v1 submitted 18 January, 2024;
originally announced January 2024.
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Out-of-equilibrium charge redistribution in a copper-oxide based superconductor by time-resolved X-ray photoelectron spectroscopy
Authors:
Denny Puntel,
Dmytro Kutnyakhov,
Lukas Wenthaus,
Markus Scholz,
Nils O. Wind,
Michael Heber,
Günter Brenner,
Genda Gu,
Robert J. Cava,
Wibke Bronsch,
Federico Cilento,
Fulvio Parmigiani,
Federico Pressacco
Abstract:
Charge-transfer excitations are of paramount importance for understanding the electronic structure of copper-oxide based high-temperature superconductors. In this study, we investigate the response of a Bi$_2$Sr$_2$CaCu$_2$O$_{\mathrm{8}+ δ}$ crystal to the charge redistribution induced by an infrared ultrashort pulse. Element-selective time-resolved core-level photoelectron spectroscopy with a hi…
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Charge-transfer excitations are of paramount importance for understanding the electronic structure of copper-oxide based high-temperature superconductors. In this study, we investigate the response of a Bi$_2$Sr$_2$CaCu$_2$O$_{\mathrm{8}+ δ}$ crystal to the charge redistribution induced by an infrared ultrashort pulse. Element-selective time-resolved core-level photoelectron spectroscopy with a high energy resolution allows disentangling the dynamics of oxygen ions with different coordination and bonds thanks to their different chemical shifts. Our experiment shows that the O\,$1s$ component arising from the Cu-O planes is significantly perturbed by the infrared light pulse. Conversely, the apical oxygen, also coordinated with Sr ions in the Sr-O planes, remains unaffected. This result highlights the peculiar behavior of the electronic structure of the Cu-O planes. It also unlocks the way to study the out-of-equilibrium electronic structure of copper-oxide-based high-temperature superconductors by identifying the O\,$1s$ core-level emission originating from the oxygen ions in the Cu-O planes. This ability could be critical to gain information about the strongly-correlated electron ultrafast dynamical mechanisms in the Cu-O plane in the normal and superconducting phases.
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Submitted 22 June, 2023;
originally announced June 2023.
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Real-time observation of phonon-electron energy and angular momentum flow in laser-heated nickel
Authors:
Vishal Shokeen,
Michael Heber,
Dmytro Kutnyakhov,
Xiaocui Wang,
Alexander Yaroslavtsev,
Pablo Maldonado,
Marco Berritta,
Nils Wind,
Lukas Wenthaus,
Federico Pressacco,
Chul-Hee Min,
Matz Nissen,
Sanjoy K. Mahatha,
Siarhei Dziarzhytski,
Peter M. Oppeneer,
Kai Rossnagel,
Hans-Joachim Elmers,
Gerd Schönhense,
Hermann A. Dürr
Abstract:
Identifying the microscopic nature of non-equilibrium energy transfer mechanisms among electronic, spin and lattice degrees of freedom is central for understanding ultrafast phenomena such as manipulating magnetism on the femtosecond timescale. Here we use time and angle-resolved photoemission spectroscopy to go beyond the often-employed ensemble-averaged view of non-equilibrium dynamics in terms…
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Identifying the microscopic nature of non-equilibrium energy transfer mechanisms among electronic, spin and lattice degrees of freedom is central for understanding ultrafast phenomena such as manipulating magnetism on the femtosecond timescale. Here we use time and angle-resolved photoemission spectroscopy to go beyond the often-employed ensemble-averaged view of non-equilibrium dynamics in terms of quasiparticle temperature evolutions. We show for ferromagnetic Ni that the non-equilibrium electron and spin dynamics display pronounced variations with electron momentum whereas the magnetic exchange interaction remains isotropic. This highlights the influence of lattice-mediated scattering processes and opens a pathway towards unraveling the still elusive microscopic mechanism of spin-lattice angular momentum transfer.
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Submitted 19 December, 2023; v1 submitted 18 June, 2023;
originally announced June 2023.
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Multiplex movie of concerted rotation of molecules on a 2D material
Authors:
Kiana Baumgärtner,
Misa Nozaki,
Marvin Reuner,
Nils Wind,
Masato Haniuda,
Christian Metzger,
Michael Heber,
Dmytro Kutnyakhov,
Federico Pressacco,
Lukas Wenthaus,
Keisuke Hara,
Chul-Hee Min,
Martin Beye,
Friedrich Reinert,
Friedrich Roth,
Sanjoy Kr Mahatha,
Anders Madsen,
Tim Wehling,
Kaori Niki,
Daria Popova-Gorelova,
Kai Rossnagel,
Markus Scholz
Abstract:
Function is dynamic and originates at atomic interfaces. Combining the degrees of freedom of molecules with the peculiar properties of 2D quantum materials can create novel functionality. Here, we report the manipulation and ultrafast imaging of a unidirectional gearing motion in molecules on a 2D quantum material. To visualize and disentangle the intertwined structural and electronic dynamics of…
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Function is dynamic and originates at atomic interfaces. Combining the degrees of freedom of molecules with the peculiar properties of 2D quantum materials can create novel functionality. Here, we report the manipulation and ultrafast imaging of a unidirectional gearing motion in molecules on a 2D quantum material. To visualize and disentangle the intertwined structural and electronic dynamics of such a hybrid interface, we record a 'full molecular movie' by imaging the atomic positions, the evolution of the molecular orbital wavefunctions and the modification of electronic states of the substrate. In a multimodal investigation in a single setup, we disentangle dynamics in valence and core electrons of both the molecule and the surface with femtosecond and sub-ångström precision. The ultrafast rotational motion is fueled by the transfer of hot holes into the molecules that results in 'supercharging' of the film. As hot carriers move through the interface, we track a transient modification of the frontier molecular orbitals and observe a chiral symmetry breaking associated with local structural rearrangements. Our calculations show that the 'supercharging' changes the interfacial potential energy landscape and triggers the gearing motion. The experiment offers all-in-one imaging of the electronic, molecular orbital, chemical and structural dynamics during the flow of charge and energy across the hybrid interface. Our approach provides detailed dynamical information on the mechanism underlying surface-adsorbed molecular gears and enables tailoring novel functionalities in hybrid active matter.
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Submitted 12 May, 2023;
originally announced May 2023.
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Tracking the surface atomic motion in a coherent phonon oscillation
Authors:
Davide Curcio,
Klara Volckaert,
Dmytro Kutnyakhov,
Steinn Ymir Agustsson,
Kevin Bühlmann,
Federico Pressacco,
Michael Heber,
Siarhei Dziarzhytski,
Yves Acremann,
Jure Demsar,
Wilfried Wurth,
Charlotte E. Sanders,
Philip Hofmann
Abstract:
X-ray photoelectron diffraction is a powerful tool for determining the structure of clean and adsorbate-covered surfaces. Extending the technique into the ultrafast time domain will open the door to studies as diverse as the direct determination of the electron-phonon coupling strength in solids and the mapping of atomic motion in surface chemical reactions. Here we demonstrate time-resolved photo…
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X-ray photoelectron diffraction is a powerful tool for determining the structure of clean and adsorbate-covered surfaces. Extending the technique into the ultrafast time domain will open the door to studies as diverse as the direct determination of the electron-phonon coupling strength in solids and the mapping of atomic motion in surface chemical reactions. Here we demonstrate time-resolved photoelectron diffraction using ultrashort soft X-ray pulses from the free electron laser FLASH. We collect Se 3d photoelectron diffraction patterns over a wide angular range from optically excited Bi$_2$Se$_3$ with a time resolution of 140 fs. Combining these with multiple scattering simulations allows us to track the motion of near-surface atoms within the first 3 ps after triggering a coherent vibration of the A$_{1g}$ optical phonons. Using a fluence of 4.2 mJ/cm$^2$ from a 1.55 eV pump laser, we find the resulting coherent vibrational amplitude in the first two interlayer spacings to be on the order of 1 pm.
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Submitted 26 May, 2022;
originally announced May 2022.
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Multispectral time-resolved energy-momentum microscopy using high-harmonic extreme ultraviolet radiation
Authors:
Michael Heber,
Nils Wind,
Dmytro Kutnyakhov,
Federico Pressacco,
Tiberiu Arion,
Friedrich Roth,
Wolfgang Eberhardt,
Kai Rossnagel
Abstract:
A 790-nm-driven high-harmonic generation source with a repetition rate of 6 kHz is combined with a toroidal-grating monochromator and a high-detection-efficiency photoelectron time-of-flight momentum microscope to enable time- and momentum-resolved photoemission spectroscopy over a spectral range of $23.6$-$45.5$ eV with sub-100-fs time resolution. Three-dimensional (3D) Fermi surface mapping is d…
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A 790-nm-driven high-harmonic generation source with a repetition rate of 6 kHz is combined with a toroidal-grating monochromator and a high-detection-efficiency photoelectron time-of-flight momentum microscope to enable time- and momentum-resolved photoemission spectroscopy over a spectral range of $23.6$-$45.5$ eV with sub-100-fs time resolution. Three-dimensional (3D) Fermi surface mapping is demonstrated on graphene-covered Ir(111) with energy and momentum resolutions of $\lesssim$$100$ meV and $\lesssim$$0.1$ $Å^{-1}$, respectively. The table-top experiment sets the stage for measuring the $k_z$-dependent ultrafast dynamics of 3D electronic structure, including band structure, Fermi surface, and carrier dynamics in 3D materials as well as 3D orbital dynamics in molecular layers.
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Submitted 19 July, 2022; v1 submitted 21 March, 2022;
originally announced March 2022.
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Subpicosecond metamagnetic phase transition driven by non-equilibrium electron dynamics
Authors:
Federico Pressacco,
Davide Sangalli,
Vojtěch Uhlíř,
Dmytro Kutnyakhov,
Jon Ander Arregi,
Steinn Ymir Agustsson,
Günter Brenner,
Harald Redlin,
Michael Heber,
Dmitry Vasilyev,
Jure Demsar,
Gerd Schönhense,
Matteo Gatti,
Andrea Marini,
Wilfried Wurth,
Fausto Sirotti
Abstract:
Femtosecond light-induced phase transitions between different macroscopic orders provide the possibility to tune the functional properties of condensed matter on ultrafast timescales. In first-order phase transitions, transient non-equilibrium phases and inherent phase coexistence often preclude non-ambiguous detection of transition precursors and their temporal onset. Here, we present a study com…
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Femtosecond light-induced phase transitions between different macroscopic orders provide the possibility to tune the functional properties of condensed matter on ultrafast timescales. In first-order phase transitions, transient non-equilibrium phases and inherent phase coexistence often preclude non-ambiguous detection of transition precursors and their temporal onset. Here, we present a study combining time-resolved photoelectron spectroscopy and ab-initio electron dynamics calculations elucidating the transient subpicosecond processes governing the photoinduced generation of ferromagnetic order in antiferromagnetic FeRh. The transient photoemission spectra are accounted for by assuming that not only the occupation of electronic states is modified during the photoexcitation process. Instead, the photo-generated non-thermal distribution of electrons modifies the electronic band structure. The ferromagnetic phase of FeRh, characterized by a minority band near the Fermi energy, is established 350+- 30 fs after the laser excitation. Ab-initio calculations indicate that the phase transition is initiated by a photoinduced Rh-to-Fe charge transfer.
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Submitted 18 February, 2021;
originally announced February 2021.
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Observation of an excitonic Mott transition through ultrafast core-$\textit{cum}$-conduction photoemission spectroscopy
Authors:
Maciej Dendzik,
R. Patrick Xian,
Enrico Perfetto,
Davide Sangalli,
Dmytro Kutnyakhov,
Shuo Dong,
Samuel Beaulieu,
Tommaso Pincelli,
Federico Pressacco,
Davide Curcio,
Steinn Ymir Agustsson,
Michael Heber,
Jasper Hauer,
Wilfried Wurth,
Günter Brenner,
Yves Acremann,
Philip Hofmann,
Martin Wolf,
Andrea Marini,
Gianluca Stefanucci,
Laurenz Rettig,
Ralph Ernstorfer
Abstract:
Time-resolved soft-X-ray photoemission spectroscopy is used to simultaneously measure the ultrafast dynamics of core-level spectral functions and excited states upon excitation of excitons in WSe$_2$. We present a many-body approximation for the Green's function, which excellently describes the transient core-hole spectral function. The relative dynamics of excited-state signal and core levels rev…
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Time-resolved soft-X-ray photoemission spectroscopy is used to simultaneously measure the ultrafast dynamics of core-level spectral functions and excited states upon excitation of excitons in WSe$_2$. We present a many-body approximation for the Green's function, which excellently describes the transient core-hole spectral function. The relative dynamics of excited-state signal and core levels reveals a delayed core-hole renormalization due to screening by excited quasi-free carriers, revealing an excitonic Mott transition. These findings establish time-resolved core-level photoelectron spectroscopy as a sensitive probe of subtle electronic many-body interactions and an ultrafast electronic phase transition.
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Submitted 28 March, 2020;
originally announced March 2020.
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An open-source, end-to-end workflow for multidimensional photoemission spectroscopy
Authors:
Rui Patrick Xian,
Yves Acremann,
Steinn Ymir Agustsson,
Maciej Dendzik,
Kevin Bühlmann,
Davide Curcio,
Dmytro Kutnyakhov,
Frederico Pressacco,
Michael Heber,
Shuo Dong,
Tommaso Pincelli,
Jure Demsar,
Wilfried Wurth,
Philip Hofmann,
Martin Wolf,
Markus Scheidgen,
Laurenz Rettig,
Ralph Ernstorfer
Abstract:
Characterization of the electronic band structure of solid state materials is routinely performed using photoemission spectroscopy. Recent advancements in short-wavelength light sources and electron detectors give rise to multidimensional photoemission spectroscopy, allowing parallel measurements of the electron spectral function simultaneously in energy, two momentum components and additional phy…
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Characterization of the electronic band structure of solid state materials is routinely performed using photoemission spectroscopy. Recent advancements in short-wavelength light sources and electron detectors give rise to multidimensional photoemission spectroscopy, allowing parallel measurements of the electron spectral function simultaneously in energy, two momentum components and additional physical parameters with single-event detection capability. Efficient processing of the photoelectron event streams at a rate of up to tens of megabytes per second will enable rapid band mapping for materials characterization. We describe an open-source workflow that allows user interaction with billion-count single-electron events in photoemission band mapping experiments, compatible with beamlines at $3^{\text{rd}}$ and $4^{\text{th}}$ generation light sources and table-top laser-based setups. The workflow offers an end-to-end recipe from distributed operations on single-event data to structured formats for downstream scientific tasks and storage to materials science database integration. Both the workflow and processed data can be archived for reuse, providing the infrastructure for documenting the provenance and lineage of photoemission data for future high-throughput experiments.
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Submitted 14 November, 2020; v1 submitted 17 September, 2019;
originally announced September 2019.
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Ultrafast molecular orbital tomography of a pentacene thin film using time-resolved momentum microscopy at a free-electron laser
Authors:
K. Baumgärtner,
M. Reuner,
C. Metzger,
D. Kutnyakhov,
M. Heber,
C. H. Min,
T. R. F. Peixoto,
M. Reiser,
C. Kim,
W. Lu,
R. Shayduk,
W. M. Izquierdo,
G. Brenner,
F. Roth,
F. Pressacco,
A. Schöll,
S. Molodtsov,
W. Wurth,
F. Reinert,
A. Madsen,
D. Popova-Gorelova,
M. Scholz
Abstract:
We use time-resolved momentum microscopy at a free-electron laser (FEL) and extend orbital tomography into the time domain to image the electronic wave functions of excited molecular orbitals. This technique provides unprecedented insight into the ultrafast interplay between structural and electronic dynamics. In this work we prove general applicability and establish the experimental conditions at…
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We use time-resolved momentum microscopy at a free-electron laser (FEL) and extend orbital tomography into the time domain to image the electronic wave functions of excited molecular orbitals. This technique provides unprecedented insight into the ultrafast interplay between structural and electronic dynamics. In this work we prove general applicability and establish the experimental conditions at FEL sources to minimize space charge effects and radiation damage. We investigate a bilayer pentacene film on Ag(110) by optical laser pump and FEL probe experiments. From the momentum microscopy signal, we obtain time-dependent momentum maps of the excited-state dynamics of both pentacene layers separately. Combining experimental observations with a theoretical study, we interpret the observed signal for the bottom layer as resulting from the charge redistribution between the molecule and the substrate induced by excitation. We identify that the dynamics of the top pentacene layer resembles excited-state molecular dynamics.
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Submitted 3 December, 2021; v1 submitted 24 July, 2019;
originally announced July 2019.
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Time- and momentum-resolved photoemission studies using time-of-flight momentum microscopy at a free-electron laser
Authors:
Dmytro Kutnyakhov,
Rui Patrick Xian,
Maciej Dendzik,
Michael Heber,
Federico Pressacco,
Steinn Ymir Agustsson,
Lukas Wenthaus,
Holger Meyer,
Sven Gieschen,
Giuseppe Mercurio,
Adrian Benz,
Kevin Bühlman,
Simon Däster,
Rafael Gort,
Davide Curcio,
Klara Volckaert,
Marco Bianchi,
Charlotte Sanders,
Jill Atsuko Miwa,
Søren Ulstrup,
Andreas Oelsner,
Christian Tusche,
Ying-Jiun Chen,
Dmitrii Vasilyev,
Katerina Medjanik
, et al. (16 additional authors not shown)
Abstract:
Time-resolved photoemission with ultrafast pump and probe pulses is an emerging technique with wide application potential. Real-time recording of non-equilibrium electronic processes, transient states in chemical reactions or the interplay of electronic and structural dynamics offers fascinating opportunities for future research. Combining valence-band and core-level spectroscopy with photoelectro…
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Time-resolved photoemission with ultrafast pump and probe pulses is an emerging technique with wide application potential. Real-time recording of non-equilibrium electronic processes, transient states in chemical reactions or the interplay of electronic and structural dynamics offers fascinating opportunities for future research. Combining valence-band and core-level spectroscopy with photoelectron diffraction for electronic, chemical and structural analysis requires few 10 fs soft X-ray pulses with some 10 meV spectral resolution, which are currently available at high repetition rate free-electron lasers. The PG2 beamline at FLASH (DESY, Hamburg) provides a high pulse rate of 5000 pulses/s, 60 fs pulse duration and 40 meV bandwidth in an energy range of 25-830 eV with a photon beam size down to 50 microns in diameter. We have constructed and optimized a versatile setup commissioned at FLASH/PG2 that combines FEL capabilities together with a multidimensional recording scheme for photoemission studies. We use a full-field imaging momentum microscope with time-of-flight energy recording as the detector for mapping of 3D band structures in ($k_x$, $k_y$, $E$) parameter space with unprecedented efficiency. Our instrument can image full surface Brillouin zones with up to 7 Å $^{-1}$ diameter in a binding-energy range of several eV, resolving about $2.5\times10^5$ data voxels. As an example, we present results for the ultrafast excited state dynamics in the model van der Waals semiconductor WSe$_2$.
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Submitted 18 September, 2019; v1 submitted 28 June, 2019;
originally announced June 2019.
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Wave-vector dependent intensity variations of the Kondo peak in photoemission from CePd$_3$
Authors:
S. Danzenbächer,
Yu. Kucherenko,
M. Heber,
D. V. Vyalikh,
S. L. Molodtsov,
V. D. P. Servedio,
C. Laubschat
Abstract:
Strong angle-dependent intensity variations of the Fermi-level feature are observed in 4d - 4f resonant photoemission spectra of CePd$_3$(111), that reveal the periodicity of the lattice and largest intensity close to the Gamma points of the surface Brillouin zone. In the framework of a simplified periodic Anderson model the phenomena may quantitatively be described by a wave-vector dependence o…
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Strong angle-dependent intensity variations of the Fermi-level feature are observed in 4d - 4f resonant photoemission spectra of CePd$_3$(111), that reveal the periodicity of the lattice and largest intensity close to the Gamma points of the surface Brillouin zone. In the framework of a simplified periodic Anderson model the phenomena may quantitatively be described by a wave-vector dependence of the electron hopping matrix elements caused by Fermi-level crossings of non-4f-derived energy bands.
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Submitted 8 June, 2005;
originally announced June 2005.