A5075050525- Laser-Matter Interactions and Applications
- Spectroscopy and Quantum Chemical Studies
- Advanced Fiber Laser Technologies
- Advanced X-ray Imaging Techniques
- Atomic and Molecular Physics
- Crystallography and Radiation Phenomena
- Atomic and Subatomic Physics Research
- Advanced Chemical Physics Studies
- X-ray Spectroscopy and Fluorescence Analysis
- Spectroscopy Techniques in Biomedical and Chemical Research
- Advanced Electron Microscopy Techniques and Applications
- Spectroscopy and Laser Applications
- Mechanical and Optical Resonators
- Photochemistry and Electron Transfer Studies
- Quantum optics and atomic interactions
- Cold Atom Physics and Bose-Einstein Condensates
- Particle Accelerators and Free-Electron Lasers
- Porphyrin and Phthalocyanine Chemistry
- Laser-Plasma Interactions and Diagnostics
- Magnetism in coordination complexes
- Various Chemistry Research Topics
- Laser-induced spectroscopy and plasma
- Gyrotron and Vacuum Electronics Research
- Scientific Research and Discoveries
- Strong Light-Matter Interactions
Aarhus University
2023-2024
University of California, Irvine
2019-2023
Max Planck Institute for Nuclear Physics
2012-2021
University of California System
2021
Irvine Valley College
2021
Max Planck Society
2013-2015
Torino e-district
2011
Abstract Quantum optics with X-rays has long been a somewhat exotic activity, but it is now rapidly becoming relevant as precision x-ray and novel X-ray light sources, high-intensity lasers are available. This article gives an overview of the current state field outlook to future prospects. Keywords: quantum opticsparametric down conversionsingle-photon superradiancecollective Lamb shiftcoherent controlEITresonance fluorescence Acknowledgements work was supported by U.S. Department Energy,...
The reconstruction of the full temporal dipole response a strongly driven time-dependent system from single absorption spectrum is demonstrated, only requiring that sufficiently short pulse employed to initialize coherent excitation system. We apply this finding time-domain observation Rabi cycling between doubly excited atomic states in few-femtosecond regime. This allows us pinpoint breakdown few-level quantum dynamics at critical laser intensity near $2\text{ }\text{...
The spectrum of resonance fluorescence is calculated for a two-level system excited by an intense, ultrashort x-ray pulse made available instance free-electron lasers such as the Linac Coherent Light Source. We allow inner-shell hole decay widths and destruction further photoionization. This description employed to model neon cations strongly driven x rays tuned 1s 2p-1 --> 1s-1 2p transition at 848 eV; induce Rabi oscillations which are so fast that they compete with Ne 1s-hole decay....
A discrepancy between atomic theory and laboratory astrophysics experiments measuring the x-ray emission lines from highly charged Iron ions can be resolved by including nonlinear dynamical light-atom interactions.
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...
The evolution of a V-type three-level system is studied, whose two resonances are coherently excited and coupled by ultrashort laser pump probe pulses, separated varying time delay. We relate the quantum dynamics multilevel to absorption spectrum transmitted pulse. In particular, analyzing system, we interpret how atomic phases differently encoded in time-delay-dependent spectral profiles when pulse either precedes or follows This scheme experimentally applied Rb, fine-structure-split 5s...
Significance Monitoring the real-space motion of electrons directly involved in ultrafast molecular dynamics is a challenging goal, hindered by strong contributions remaining inactive electrons. Molecular quantum coherences can provide direct window into elementary electronic dynamics, but they could not be separately imaged so far. Here, we demonstrate time- and frequency-resolved X-ray diffraction technique, which employ existing stochastic pulses to image coherence contributions. The...
Direct imaging of the ultrafast quantum motion valence electrons in molecules is essential for understanding many elementary chemical and physical processes. We present a simulation study valence-electron dynamics oxazole. A valence-state electronic wavepacket prepared with an attosecond soft X-ray pulse through stimulated resonant Raman process then probed time-resolved off-resonant single-molecule diffraction. find that time dependent diffraction signal originates solely from coherences...
Tracing the evolution of molecular coherences can provide a direct, unambiguous probe nonadiabatic processes, such as passage through conical intersections electronic states. Two techniques, attosecond transient absorption spectroscopy (ATAS) and Transient Redistribution Ultrafast Electronic Coherences in Attosecond Raman Signals (TRUECARS), have been used or proposed for monitoring dynamics. Both techniques employ transmission weak extreme-ultraviolet X-ray to interrogate molecule at...
Numerous few-electron atomic systems are considered which can be used effectively for observing a potential variation of the fine-structure constant $\ensuremath{\alpha}$ and electron-proton mass ratio ${m}_{e}/{m}_{p}$. We examine optical magnetic dipole transitions between hyperfine-structure components in heavy highly charged H-like Li-like ions with observably high sensitivity to The experimental spectra proposed consist strong single line, simplifies significantly data analysis shortens...
Time-resolved photoelectron spectroscopy (TRPES) signals that monitor the relaxation of RNA base uracil upon optical excitation are simulated. Distinguishable signatures coherence dynamics at conical intersections identified, with temporal and spectral resolutions determined by duration ionizing probe pulse. The frequency resolution technique, either directly provided signal or retrieved data-processing stage, can magnify contribution from molecular coherences, enabling extraction most...
An x-ray pulse-shaping scheme is put forward for imprinting an optical frequency comb onto the radiation emitted on a driven transition, thus producing comb. A four-level system used to describe level structure of $N$ ions by narrow-bandwidth x rays, auxiliary laser, and By including many-particle enhancement resonance fluorescence, spectrum predicted consisting equally spaced narrow lines which are centered transition energy separated same tooth spacing as driving Given reference frequency,...
A scheme to infer the temporal coherence of EUV frequency combs generated from intracavity high-order harmonic generation is put forward. The excitation dynamics highly charged Mg-like ions, which interact with pulse trains featuring different carrier-envelope-phase fluctuations, are simulated. While demonstrating microscopic origin macroscopic equivalence between excitations induced by and continuous-wave lasers, we show that time train can be determined spectrum excitations. will provide a...
We demonstrate how optical cavities can be exploited to control both valence- and core-excitations in a prototypical model transition metal complex, ferricyanide ([Fe(<sc>iii</sc>)(CN)<sub>6</sub>]<sup>3−</sup>), an aqueous environment.
Resonant stimulated X-ray Raman spectroscopy of the bimetallic [MnIIIMnIV(μ-O)2(μ-OAC)(tacn)2]2+ manganese complex is investigated in a simulation study. Essential biological processes, including water oxidation photosynthesis, involve charge transfer between sites different states. We study prototypical binuclear mixed-valence transition-metal with two Mn atoms states surrounded by ligand structures and employ pump–probe sequence resonant excitations to follow occurring molecule. This...
We theoretically monitor the photoinduced ππ* → nπ* internal conversion process in 4-thiouracil (4TU), triggered by an optical pump. The element-sensitive spectroscopic signatures are recorded a resonant X-ray probe tuned to sulfur, oxygen, or nitrogen K-edge. employ high-level electronic structure methods optimized for core-excited calculation combined with quantum nuclear wavepacket dynamics computed on two relevant modes, fully accounting their nature of motions. critically discuss...
Abstract A scheme is put forward to generate fully coherent x-ray lasers based on population inversion in highly charged ions, created by fast inner-shell photoionization using broadband free-electron-laser (XFEL) pulses a laser-produced plasma. Numerical simulations the Maxwell–Bloch theory show that one can obtain high-intensity, femtosecond of relative bandwidths Δ ω / = 10 −5 –10 −7 , orders magnitude narrower than for discrete wavelengths down sub-ångström regime. Such be applicable...
A general mechanism for the generation of frequency combs referenced to atomic resonances is put forward. The based on periodic phase control a quantum systemʼs dipole response. We develop an analytic description combʼs spectral structure, depending both its and phase-control properties. further suggest experimental implementation our scheme, i.e. generating comb in soft x-ray region, which can be realized with currently available techniques radiation sources. universality this allows...
Resonant X-ray sum-frequency generation is calculated for excitations of the fluorine and oxygen core K-edge in acetyl fluoride using real-time time-dependent density functional theory. The signal generated by an extreme-ultraviolet pulse followed with variable delay T. tuned to different element-specific used probe dynamics a valence electronic wave packet. A two-dimensional recorded depending on dispersed frequency conjugated T, revealing couplings between excited states. Molecular orbital...
Temporal and spectral resolution of x-ray spectroscopy can be improved by exploiting correlations existing stochastic fields, allowing for new investigations electron nuclear dynamics in molecules.
The ground-state properties of attractive bosons trapped in a ring lattice including single potential well with an adjustable depth are investigated.The energy spectrum is reconstructed both the strong-interaction limit and superfluid regime within Bogoliubov picture.The analytical results thus obtained compared those found numerically from exact Hamiltonian, order to identify regions parameter space where this picture effective.The introduced simplest way break translational symmetry...
Strong-field quantum-state control is investigated, taking advantage of the full---amplitude and phase---characterization interaction between matter intense ultrashort pulses via transient-absorption spectroscopy. As an example, we apply method to a nondegenerate $V$-type three-level system modeling atomic Rb, use sequence delayed pulses, whose parameters are tailored steer into desired quantum state. We show how experimentally enable this optimization by retrieving all features light-matter...