Leon Kaiser

Goethe University Frankfurt

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T. Jahnke

European X-Ray Free-Electron Laser

R. Dörner

Goethe University Frankfurt

Florian Trinter

Fritz Haber Institute of the Max Planck Society

M. S. Schöffler

Goethe University Frankfurt

Sven Grundmann

Goethe University Frankfurt

K. Fehre

Goethe University Frankfurt

M. Kircher

Goethe University Frankfurt

A. Pier

Goethe University Frankfurt

N. Strenger

Goethe University Frankfurt

D. Trabert

Goethe University Frankfurt

Cooperative Institutions

Goethe University Frankfurt

University of Oxford

Max Planck Institute for Nuclear Physics

Tohoku University

Goethe Institute

European X-Ray Free-Electron Laser

Deutsches Elektronen-Synchrotron DESY

SPring-8

University of Connecticut

Aarhus University

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Revealing the two-electron cusp in the ground states of He and H2 via quasifree double photoionization

Physical Review Research (2020)

Sven Grundmann Vladislav V. Serov Florian Trinter K. Fehre N. Strenger

This work studies quasifree double photoionization using reaction microscopy and companion $a\phantom{\rule{0}{0ex}}b$ $i\phantom{\rule{0}{0ex}}n\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}t\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}o$ calculations. The quasifree mechanism is confirmed for H${}_{2}$ and introduced as a probe for the electron-electron cusp density in the ground state of a two-electron target.

10.1103/physrevresearch.2.033080

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Citations (8)

Measuring the photoelectron emission delay in the molecular frame

Nature Communications (2021)

J. Rist Kim Klyssek Nikolay M. Novikovskiy M. Kircher Isabel Vela-Peréz

If matter absorbs a photon of sufficient energy it emits an electron. The question of the duration of the emission process has intrigued scientists for decades. With the advent of attosecond metrology, experiments addressing such ultrashort intervals became possible. While these types of studies require attosecond experimental precision, we present here a novel measurement approach that avoids those experimental difficulties. We instead extract the emission delay from the interference pattern generated as the emitted photoelectron is diffracted by the parent ion's potential. Targeting core electrons in CO, we measured a 2d map of photoelectron emission delays in the molecular frame over a wide range of electron energies. The measured emission times depend drastically on the emission direction and exhibit characteristic changes along the shape resonance of the molecule. Our approach can be routinely extended to other electron orbitals and more complex molecules.

Attosecond

Photon energy

10.1038/s41467-021-26994-2

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Time-resolved photoelectron-diffraction imaging of methanol photodissociation involving molecular-hydrogen ejection

Physical Chemistry Chemical Physics (2024)

Kazuki Yoshikawa Manabu Kanno Hao Xue Naoki Kishimoto Soki Goto

We explore time- and momentum-resolved photoelectron diffraction imaging (TMR-PED) to visualize hydrogen dynamics during methanol dication dissociation. Our approach allows real-time tracking of hydrogen migration and molecular fragmentation.

10.1039/d4cp01015a

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Zeptosecond birth time delay in molecular photoionization

Science (2020)

Sven Grundmann D. Trabert K. Fehre N. Strenger A. Pier

Photoionization is one of the fundamental light-matter interaction processes in which the absorption of a photon launches the escape of an electron. The time scale of this process poses many open questions. Experiments have found time delays in the attosecond (10-18 seconds) domain between electron ejection from different orbitals, from different electronic bands, or in different directions. Here, we demonstrate that, across a molecular orbital, the electron is not launched at the same time. Rather, the birth time depends on the travel time of the photon across the molecule, which is 247 zeptoseconds (1 zeptosecond = 10-21 seconds) for the average bond length of molecular hydrogen. Using an electron interferometric technique, we resolve this birth time delay between electron emission from the two centers of the hydrogen molecule.

10.1126/science.abb9318

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Citations (32)

Quasifree Photoionization under the Reaction Microscope

Atoms (2022)

Sven Grundmann Florian Trinter Yong-Kang Fang K. Fehre N. Strenger

We experimentally investigated the quasifree mechanism (QFM) in one-photon double ionization of He and H2 at 800 eV photon energy and circular polarization with a COLTRIMS reaction microscope. Our work provides new insight into this elusive photoionization mechanism that was predicted by Miron Amusia more than four decades ago. We found the distinct four-fold symmetry in the angular emission pattern of QFM electrons from H2 double ionization that has previously only been observed for He. Furthermore, we provide experimental evidence that the photon momentum is not imparted onto the center of mass in quasifree photoionization, which is in contrast to the situation in single ionization and in double ionization mediated by the shake-off and knock-out mechanisms. This finding is substantiated by numerical results obtained by solving the system’s full-dimensional time-dependent Schrödinger equation beyond the dipole approximation.

Photon energy

Double ionization

Discrete dipole approximation

10.3390/atoms10030068

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Multi-channel photodissociation and XUV-induced charge transfer dynamics in strong-field-ionized methyl iodide studied with time-resolved recoil-frame covariance imaging

Faraday Discussions (2020)

Felix Allum N. Anders M. Brouard P. H. Bucksbaum Michael Burt

The photodissociation dynamics of strong-field ionized methyl iodide were probed using intense extreme ultraviolet (XUV) radiation produced by the SPring-8 Angstrom Compact free electron LAser.

Recoil

Methyl iodide

Extreme ultraviolet

10.1039/d0fd00115e

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Akute nekrotisierende Pankreatitis mit hämorrhagischem Schock bei sekundärer Milzruptur: Ein Fallbericht und Literaturübersicht

Zeitschrift für Gastroenterologie (2023)

Leon Kaiser Golo Petzold Ali Seif Amir Hosseini Volker Ellenrieder Albrecht Neeße

Zusammenfassung Die atraumatische Milzruptur ist eine seltene Komplikation der akuten und chronischen Pankreatitis. Sie entsteht aufgrund ihrer anatomischen Nähe zum Pankreas, beispielsweise als Folge der Erosion großer Pseudozysten oder Walled-of-Nekrosen (WON). Im Folgenden beschreiben wir den Fall einer 62-jährigen Patientin, welche sich zur weiteren Diagnostik und Therapie einer akuten Pankreatitis mit Ausbildung einer großen Walled-of-Nekrose (WON) im Pankreaskorpus und -schwanz vorstellte. Im Verlauf entwickelte die Patientin einen hämorrhagischen Schock. Eine Notfall-Computertomografie (CT) des Abdomens zeigte eine Milzruptur mit großem Kapselhämatom ohne den Nachweis einer aktiven Blutung. Im Gegensatz zu bereits publizierten Fällen wurde die Patientin ausschließlich minimalinvasiv therapiert: mittels radiologisch gesteuerter langstreckiger Embolisation der Arteria lienalis und mittels endosonografisch angelegtem Lumen-apposing Metall Stent (LAMS). Das Kapselhämatom zeigte sich unter einer Watch-and-wait-Strategie ohne sekundäre Drainage regredient.

10.1055/a-2003-9694

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Citations (1)