A5058738929- Laser-Matter Interactions and Applications
- Spectroscopy and Quantum Chemical Studies
- Advanced Chemical Physics Studies
- Advanced Electron Microscopy Techniques and Applications
- Advanced X-ray Imaging Techniques
- Atomic and Molecular Physics
- Mass Spectrometry Techniques and Applications
- Advanced Fiber Laser Technologies
- Laser-Plasma Interactions and Diagnostics
- Particle Accelerators and Free-Electron Lasers
- Spectroscopy and Laser Applications
- Photosynthetic Processes and Mechanisms
- Ion-surface interactions and analysis
- Quantum chaos and dynamical systems
- Quantum optics and atomic interactions
Max Planck Institute for Nuclear Physics
2019-2024
Heidelberg University
2023
We report on the experimental observation of a strong-field dressing an autoionizing two-electron state in helium with intense extreme-ultraviolet laser pulses from free-electron laser. The asymmetric Fano line shape this transition is spectrally resolved, and we observe modifications resonance asymmetry structure for increasing free-electron-laser pulse energy order few tens Microjoules. A quantum-mechanical calculation time-dependent dipole response state, driven by classical (XUV)...
Laser-driven recollision physics is typically accessible only at field intensities high enough for tunnel ionization. Using an extreme ultraviolet pulse ionization and a near-infrared (NIR) driving of the electron wave packet lifts this limitation. This allows us to study recollisions broad range NIR with transient absorption spectroscopy, making use reconstruction time-dependent dipole moment. Comparing dynamics linear vs circular polarization, we find parameter space, where latter favors...
We demonstrate time-resolved nonlinear extreme-ultraviolet absorption spectroscopy on multiply charged ions, here applied to the doubly neon ion, driven by a phase-locked sequence of two intense free-electron laser pulses. Absorption signatures resonance lines due $2p--3d$ bound--bound transitions between spin-orbit multiplets ${^{3}P}_{0,1,2}$ and ${^{3}D}_{1,2,3}$ transiently produced ${\mathrm{Ne}}^{2+}$ ion are revealed, with time-dependent spectral changes over time-delay range...
Abstract High-intensity ultrashort pulses at extreme ultraviolet (XUV) and x-ray photon energies, delivered by state-of-the-art free-electron lasers (FELs), are revolutionizing the field of ultrafast spectroscopy. For crossing next frontiers research, precise, reliable practical photonic tools for spectro-temporal characterization becoming steadily more important. Here, we experimentally demonstrate a technique direct measurement frequency chirp extreme-ultraviolet laser based on fundamental...
Experiments selectively excite and probe specific core electrons in CH${}_{2}$I${}_{2}$ to follow the molecule's internal dynamics also pave way toward site-selective control of chemical reactions.
Measuring bound-state quantum dynamics, excited and driven by strong fields, is achievable time-resolved absorption spectroscopy. Here, a vacuum beamline for spectroscopy in the attosecond temporal extreme ultraviolet (XUV) spectral range presented, which tool observing controlling nonequilibrium electron dynamics. In particular, we introduce technique to record an XUV signal corresponding reference simultaneously, greatly improves quality. The apparatus based on common beam path design...
Abstract The laser-field-modified dipole response of the first ionization threshold helium is studied by means attosecond transient absorption spectroscopy. We resolve light-induced time-dependent structures in photoabsorption spectrum both below and above threshold. By comparing measured results to a quantum-dynamical model, we isolate contributions unbound electron these structures. They originate from couplings near-threshold bound continuum states energy shifts free electron....
The electronic and nuclear dynamics inside molecules are essential for chemical reactions, where different pathways typically unfold on ultrafast timescales. Extreme ultraviolet (XUV) light pulses generated by free-electron lasers (FELs) allow atomic-site electronic-state selectivity, triggering specific molecular while providing femtosecond resolution. Yet, time-resolved experiments either blind to neutral fragments or limited the spectral bandwidth of FEL pulses. Here, we combine a...
A setup for an all-XUV transient absorption spectroscopy at free-electron lasers, was developed and employed to explore XUV-excited dynamics XUV-driven nonlinear phenomena.
Abstract Using attosecond transient absorption spectroscopy for time delays where the near-infrared pump and extreme ultraviolet (XUV) probe pulses overlap, sub-cycle structures in build-up of lines xenon ions are investigated as a function intensity during strong-field ionization. We observe half-cycle-periodic change line-shape asymmetry ionic 4d–5p resonances. Analyzing line shapes, we find that particular phase induced dipole emission is modified, magnitude this modulation decreases with...
We report the measurement of photoelectron angular distribution two-photon single-ionization near 2p^{2} ^{1}D^{e} double-excitation resonance in helium, benchmarking fundamental nonlinear interaction two photons with correlated electrons. This observation is enabled by unique combination intense extreme ultraviolet pulses, delivered at high-repetition-rate free-electron laser Hamburg (FLASH), ionizing a jet cryogenically cooled helium atoms reaction microscope. The spectral structure...
We performed a time-resolved spectroscopy experiment on the dissociation of oxygen molecules after interaction with intense extreme-ultraviolet (XUV) light from free-electron laser in Hamburg at Deutsches Elektronen-Synchrotron. Using an XUV-pump/XUV-probe transient-absorption geometry split-and-delay unit, we observe onset electronic transitions O2+ cation near 50 eV photon energy, marking end progression molecule to two isolated atoms. different time scales 290 ± 53 and 180 76 fs for...
Abstract Two-electron dynamics of an excited model atom interacting with moderately strong laser fields is analyzed in the time domain. We solve time-dependent Schrödinger equation (TDSE) for two electrons confined to same one-dimensional configuration space, accounting also electron-electron interaction. The computational method allows direct access population relevant atomic states during and right after interaction a near-infrared (NIR) pulse. compare ionization singly doubly states. find...
The authors study the ultrafast buildup of a doubly excited Rydberg series in helium. They observe how individual resonances emerge out continuous background absorption and quantify time for spectral lines to be separated.
The electronic structure of atomic quantum systems and their dynamical interaction with light is reflected in transition dipole matrix elements coupling the system's energy eigenstates. In this work, we measure phase shifts time-dependent ultrafast absorption to determine relative signs of. transition-dipole elements. measurement relies on precise absolute calibration timing between used pulses, which achieved by combining attosecond transient streaking spectroscopy simultaneously resonant...
We observe and modify a molecular vibrational wave packet in an electronically excited state of the neutral hydrogen molecule. In extreme-ultraviolet (XUV) time-domain absorption spectroscopy experiment, we launch <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:mrow><a:mi>D</a:mi><a:mmultiscripts><a:mi mathvariant="normal">Π</a:mi><a:mi>u</a:mi><a:none/><a:mprescripts/><a:none/><a:mn>1</a:mn></a:mmultiscripts><a:mspace width="0.16em"/><a:mn>3</a:mn><a:mi...
Accessing attosecond (as) dynamics directly in the time domain has been achieved by several pioneering experiments over course of last decade. Extreme ultraviolet (XUV) group delays and, later, ionization on order a few attoseconds have extracted photoemission or high-harmonic spectroscopy. Here, we present and benchmark an approach based transient absorption spectroscopy to quantify deliberately induced employing resonant photoexcitation three XUV transitions with precision less than 5 as....
We observe and control a molecular vibrational wave packet in an electronically excited state of the neutral hydrogen molecule. In extreme-ultraviolet (XUV) transient-absorption experiment we launch $D ^1\Pi_u 3p\pi$ H$_2$ its time evolution via coherent dipole response. The reconstructed time-dependent from experimentally measured XUV absorption spectra provides access to revival packet, which intense near-infrared (NIR) pulse. Tuning intensity NIR pulse be significantly modified, is...
We present a technique for the direct measurement of frequency chirp high-frequency free-electron-laser pulses based on fundamental nonlinear optics. It is implemented in transient absorption geometry.