A5038305308- Atomic and Molecular Physics
- Advanced Chemical Physics Studies
- Particle Accelerators and Free-Electron Lasers
- Mass Spectrometry Techniques and Applications
- Particle accelerators and beam dynamics
- Advanced X-ray Imaging Techniques
- X-ray Spectroscopy and Fluorescence Analysis
- Laser-Matter Interactions and Applications
- Electron and X-Ray Spectroscopy Techniques
- Laser-Plasma Interactions and Diagnostics
- Superconducting Materials and Applications
- Nuclear Physics and Applications
- Spectroscopy and Quantum Chemical Studies
- Ion-surface interactions and analysis
- Crystallography and Radiation Phenomena
- Fullerene Chemistry and Applications
- Cold Atom Physics and Bose-Einstein Condensates
- Gyrotron and Vacuum Electronics Research
- Nuclear physics research studies
- Photocathodes and Microchannel Plates
- Orbital Angular Momentum in Optics
- Advanced Electron Microscopy Techniques and Applications
- Radiation Detection and Scintillator Technologies
- Graphene research and applications
- Advanced X-ray and CT Imaging
SAGA Light Source
2016-2025
Institute for Molecular Science
2007-2024
National Institutes of Natural Sciences
2024
Sophia University
2017-2020
University of Toyama
2017-2020
High Energy Accelerator Research Organization
2017-2020
Institute of Materials Structure Science
2017-2020
Niigata University
2017
Hitachi (Japan)
2012
Japan Synchrotron Radiation Research Institute
2009-2010
We theoretically demonstrate for the first time that a single free electron in circular/spiral motion emits twisted photons carrying well defined orbital angular momentum along axis of circulation, adding to spin momentum. show that, when velocity is relativistic, radiation field contains harmonic components and l-th carry lhbar total each. This work indicates are naturally emitted by electrons more ubiquitous laboratories nature than ever been thought.
We theoretically show that a single free electron in circular/spiral motion radiates an electromagnetic wave possessing helical phase structure and carrying orbital angular momentum. experimentally demonstrate it by double-slit diffraction on radiation from relativistic electrons spiral motion. twisted photons should be created naturally cyclotron/synchrotron radiations or Compton scatterings various situations cosmic space. propose promising laboratory vortex photon sources wavelengths...
Abstract Quantum manipulation of populations and pathways in matter by light pulses, so-called coherent control, is currently one the hottest research areas optical physics photochemistry. The forefront control moving rapidly into regime extreme ultraviolet wavelength attosecond temporal resolution. This advance has been enabled development high harmonic generation sources driven intense femtosecond laser pulses advent seeded free electron sources. Synchrotron radiation, which usually...
We present a new realization of the time-domain double-slit experiment with photoelectrons, demonstrating that spontaneous radiation from bunch relativistic electrons can be used to control quantum interference single-particles. The arrangement is realized by pair light wave packets attosecond-controlled spacing, which naturally included in two undulators series. Photoelectrons emitted helium atoms are observed energy-domain under condition detecting them one one, and stochastic buildup...
We have measured optical reflection spectra for the alkali-metal fullerides ${\mathrm{K}}_{3}$${\mathrm{C}}_{60}$, ${\mathrm{Rb}}_{3}$${\mathrm{C}}_{60}$, ${\mathrm{K}}_{4}$${\mathrm{C}}_{60}$, ${\mathrm{Rb}}_{4}$${\mathrm{C}}_{60}$, and ${\mathrm{Rb}}_{6}$${\mathrm{C}}_{60}$ grown by a cosublimation method in an energy region of 0.08--6 eV. A gap structure peaked at 0.5 eV was observed indicating that this compound is insulator. This result good agreement with other kinds experiments, but...
We have studied double Auger decay after $\text{C}\text{ }1s\ensuremath{\rightarrow}2{\ensuremath{\pi}}^{\ensuremath{\ast}}$ photoexcitation in gas phase carbon monoxide. Two distinct processes, namely direct and cascade decay, are identified detail using multiple coincidence techniques. Cascade is shown to be the overall dominant process. Decay channels involving dissociation of molecule followed by autoionization oxygen fragments observed.
Photoelectron angular distributions from helium atoms are measured using the circularly polarized extreme ultraviolet (XUV) vortex produced by a helical undulator as higher harmonics of its radiation. The XUV has wave front and carries orbital momentum well spin associated with circular polarization. While violation electric dipole transition rules been predicted for interactions between vortices atoms, photoelectron reproduced assuming transitions only. This observation can be explained...
An undulator is a device widely used in synchrotron light sources to produce certain quasi-monochromatic light; however, its waveform has never been recorded due the lack of measurement techniques. Here we propose an approach characterize waveforms electric fields produced by relativistic electrons using algorithm spectral phase interferometry for direct electric-field reconstruction, which one most common methods ultrashort laser pulses. As result, have succeeded retrieving 10-cycle square...
Double photoionization (DPI) leading to double core-hole states of ${\mathrm{Xe}}^{2+}$ $4{d}^{\ensuremath{-}2}$ has been studied using a magnetic bottle time-of-flight spectrometer. The assignments the are confirmed by Auger lines extracted from fourfold coincidences including two photoelectrons and electrons. It is estimated that core-core DPI into at photon energy 301.6 eV favored cross section about 0.3 MB. intense due mixing continuum with $4p$ single photoionization, which manifested...
Auger decay of ${\mathrm{Xe}}^{+}$ states arising from $4p$ ionization has been studied with a very efficient multielectron coincidence method. Coster-Kronig $4{p}^{\ensuremath{-}1}$ and the subsequent into ${\mathrm{Xe}}^{3+}$ three valence holes are identified. Formation ${\mathrm{Xe}}^{4+}$ is also observed as quadruple coincidences between photoelectron electrons. The relative probabilities individual multi-ionization processes determined yields.
The Auger decay processes from the $1s$-core-hole state of Ne have been investigated with a multielectron coincidence method. We observed double and triple decays, in which both cascade direct are identified different ways energy sharing between electrons. Branching ratios for electronic configurations final states determined corresponding electron yields. Particularly decay, branching divided into individual contributions paths.
The observation of an optical vortex beam at 60 nm wavelength, produced as the second-harmonic radiation from a helical undulator, is reported. wavefront was verified by measuring interference pattern between undulator and normal another undulator. Although patterns were slightly blurred owing to relatively large electron emittance, it possible observe features thanks beam. experimental results well reproduced simulation.
We report the observation of quantum interference between electron wave packets launched from inner-shell $4d$ orbital Xe atom. Using pairs femtosecond radiation a synchrotron light source, we obtain time-domain interferograms for excitations. This approach enables experimental verification and control packets. Furthermore, Auger decay excited state is tracked. To best our knowledge, this first packet in an atomic process, also time-resolved experiment on few-femtosecond using source.
Electron correlations in three electron emission associated with innershell photoionization are investigated for the first time through a combined theoretical and experimental approach.Namely, different kinds of Post Collisional Interactions (PCI) occurring decay Argon 2p holes by two Auger electrons isolated experimentally powerful coincidence technique modeled an eikonal approach.It is shown that PCI distortion photoelectron line shape stronger than single paths depends critically on...
We report on an experimental investigation of energy correlation among three electrons emitted in valence triple photoionization (TPI) Ar. The correlations reveal a predominant contribution from sequential TPI processes involving intermediate ${\mathrm{Ar}}^{2+}$ formation, which suggests that such indirect contributions should be included the formulation threshold law for cross sections. differential section direct at about 150 eV above producing one slow electron with few kinetic is found...
An Auger-electron-photoion coincidence (AEPICO) method has been applied to study the stability and dissociation dynamics of dicationic states after N K-shell photoionization nitrogen molecules. From time-of-flight kinetic energy analyses product ions, we have obtained coincident Auger spectra associated with metastable N2 (++) ions dissociative leading → N(+) + N(++) N. To investigate production states, present two-dimensional AEPICO maps which reveal correlations between binding energies...
We have studied Auger decays of the 1s shake-up and shake-off states in N2 molecules with a state-of-the-art multi-electron coincidence method. The coincidences reveal overall features transitions from individual core-hole states. decay are interpreted by spectator participant roles exited electrons. It is observed that valence holes formed at initial process remain unchanged during
Simultaneous two-electron emission upon $2p$ core-electron excitation in Ar has been studied using a state-of-the-art multielectron coincidence method. effectively populates Rydberg-excited ${\text{Ar}}^{2+}$ states, which the excited electron behaves as spectator of direct double Auger decay core hole. This observation constitutes experimental evidence that shake-off mechanism is not sufficient to model hole and suggests an important contribution from knock-out mechanism.
We report on the use of pairs 10-cycle extreme ultraviolet wave packets with attosecond-controlled spacing emitted by individual relativistic electrons within an electron bunch passing through a tandem undulator. Based temporal coherent control technique circular polarization, we succeeded in controlling excited state alignment photoexcitation helium atoms, which verified observation oscillation fluorescence yield depending delay time. Our work demonstrates potential undulator radiation for...
Abstract UVSOR, a low energy synchrotron light source, has been operational for about 40 years. It providing high brightness VUV radiation to users but also research environment source developments. BL1U is dedicated beamline developments and applications of novel technologies. The equipped with two variable-polarization undulators phase-shifter magnet femto-second laser system which synchronized the RF acceleration. We have studying oscillator-type free electron laser, coherent harmonic...
Valence double photoionization of Ne atom has been investigated by multielectron spectroscopy. Complete information on energy correlation between ejected electrons allows the identification ${\mathrm{Ne}}^{2+}$ final states and their formation mechanism. In addition to simultaneous two-electron emission from valence shells, indirect processes mediated singly charged excited have observed. We first obtained direct double-photoionization cross sections state-selectively in a wide photon...
We have developed a multi-coincidence technique to study MCI–molecule collisions. Using this technique, complicated reaction processes and collision dynamics in Kr 8+ +N 2 collisions been successfully revealed the energy region below 200 eV/u. The single-, double-, tripleand quadruple-charge changing are resolved three low-energy phenomena, ‘peak-shifting’ of molecular ions, ‘peak-splitting’ ‘anisotropic fragmentation’ fragment ion pairs, found time-of-flight spectra target ions. By careful...
Double photoionization into states which have holes in one core and valence orbitals has been observed CO using a state-of-the-art multielectron coincidence method. The core-valence CO2+ structures exhibited on the electron spectra are assigned by comparison with available calculation [H. Schulte et al., J. Chem. Phys. 105, 11108 (1996)]. Features of spectrum confirm that properties characterized interaction between localized holes.