A5087242936- Muon and positron interactions and applications
- Advanced X-ray Imaging Techniques
- Crystallography and Radiation Phenomena
- Superconducting Materials and Applications
- Graphene research and applications
- Rare-earth and actinide compounds
- X-ray Spectroscopy and Fluorescence Analysis
- Magnetic Properties of Alloys
- Advanced Electron Microscopy Techniques and Applications
- Semiconductor Quantum Structures and Devices
- Magnetic and transport properties of perovskites and related materials
- Particle accelerators and beam dynamics
- Physics of Superconductivity and Magnetism
- X-ray Diffraction in Crystallography
- Electronic and Structural Properties of Oxides
- Advanced NMR Techniques and Applications
- Diamond and Carbon-based Materials Research
- Medical Imaging Techniques and Applications
- Semiconductor materials and devices
- Atomic and Molecular Physics
- Semiconductor Lasers and Optical Devices
- Advanced Condensed Matter Physics
- Photonic and Optical Devices
- Particle Accelerators and Free-Electron Lasers
- Advanced X-ray and CT Imaging
Paul Scherrer Institute
2010-2020
University of Zurich
1984-2020
Swiss Federal Laboratories for Materials Science and Technology
2017-2020
Swiss Light Source
2000-2010
SLAC National Accelerator Laboratory
2010
Paediatric Integrated Cancer Service
2007
University of California, Santa Barbara
2004
University of Minnesota
1988
Alexander T. Augusta Military Medical Center
1988
Simon Fraser University
1979-1981
The complete atomic structure of a five-monolayer film LaAlO3 on SrTiO3 has been determined for the first time by surface x-ray diffraction in conjunction with coherent Bragg rod analysis phase-retrieval method and further structural refinement. Cationic mixing at interface results dilatory distortions formation metallic La(1-x)SrxTiO3. By invoking electrostatic potential minimization, ratio Ti{4+}/Ti{3+} across was determined, from which lattice dilation could be quantitatively explained...
Positive muons implanted into diamond and zincblende-structured semiconductors often form hydrogen-like paramagnetic muonium (${\ensuremath{\mu}}^{+}\ensuremath{-}{e}^{\ensuremath{-}}$) states whose characteristics can be investigated with the "muon spin rotation" ($\ensuremath{\mu}\mathrm{SR}$) technique. In contrast to case of hydrogen, which is not known a state in semiconductors, two coexisting types are seen. "Mu" large isotropic hyperfine interaction, "${\mathrm{Mu}}^{*}$" small...
The SwissFEL X-ray Free Electron Laser (XFEL) facility started construction at the Paul Scherrer Institute (Villigen, Switzerland) in 2013 and will be ready to accept its first users 2018 on Aramis hard branch. In following sections we summarize various aspects of project, including design soft branches accelerator, results performance simulations, details photon beamlines experimental stations, our commissioning results.
The structure of a single layer graphene on Ru(0001) has been studied using surface x-ray diffraction. A surprising superstructure containing 1250 carbon atoms determined, whereby $25\ifmmode\times\else\texttimes\fi{}25$ unit cells lie $23\ifmmode\times\else\texttimes\fi{}23$ Ru. Each supercell contains $2\ifmmode\times\else\texttimes\fi{}2$ crystallographically inequivalent subcells caused by corrugation. Strong intensity oscillations in the rods demonstrate that Ru substrate is also...
The Paul Scherrer Institute is planning the construction of a hardx-ray free-electron laser, SwissFEL, by 2016, which will produce intense, ultrashort pulses transversely coherent radiation in wavelength range 0.1-7 nm, with future extensions to cover 0.08-30 nm.Special design considerations include (a) compact construction, compatible status national facility, (b) uniform 100 Hz repetition rate, well suited sample manipulations and detector readout, (c) flexible tuning electron beam energy...
We have studied precession of polarized positive muons in quartz and silicon transverse magnetic fields, via the asymmetric decay. observed free muon two-frequency muonium precession, as well two anomalous frequencies apparent only silicon.
A massive reduction in CO
Two muonium states have been found in diamond. "Normal" shows an isotropic hyperfine interaction with a coupling constant $\frac{A}{h}=3711\ifmmode\pm\else\textpm\fi{}21$ MHz. "Anomalous" is described by $〈111〉$ axially symmetric spin Hamiltonian constants extrapolated to 0 K $\frac{|{A}_{\ensuremath{\parallel}}|}{h}=167.98\ifmmode\pm\else\textpm\fi{}0.06$ MHz and $\frac{|{A}_{\ensuremath{\perp}}|}{h}=392.59\ifmmode\pm\else\textpm\fi{}0.06$ ${A}_{\ensuremath{\parallel}}$...
We report the first complete determination, using surface x-ray diffraction, of structure TiO2-terminated SrTiO3(001), both at room temperature in vacuum, and also hot, under typical conditions used for thin film growth. The cold consists a mixture (1x1) relaxation (2x1) (2x2) reconstructions. latter disappear over several minutes upon heating. structures are best modeled by TiO2-rich similar to that proposed Erdman et al. [Nature (London) 419, 55 (2002).10.1038/nature01010]. Both...
The use of an area detector in grazing-incidence X-ray experiments lends many advantages terms both speed and reliability. Here a discussion is given the procedures established using PILATUS pixel developed at Swiss Light Source for optimizing data acquisition analysis surface diffraction Materials Science beamline, especially with regard to reflectivity measurements, crystal truncation fractional order rods, experiments.
The anomalous muonium state in Si has been studied with the muon-spin rotation technique as a function of strength and orientation applied magnetic field. It was found that this is well described by spin Hamiltonian axial symmetry about [111] axis.
We present a structural analysis of the graphene/Ru(0001) system obtained by surface x-ray diffraction. The data were fitted using Fourier-series-expanded displacement fields from an ideal bulk structure plus application symmetry constraints. shape observed superstructure rods proves reconstruction substrate, induced strong bonding graphene to ruthenium. Both layer and underlying substrate are corrugated, with peak-to-peak heights (0.82±0.15) Å (0.19±0.02) for topmost Ru-atomic layer,...
The SwissFEL soft X-ray free-electron laser (FEL) beamline Athos will be ready for user operation in 2021. Its design includes a novel layout of alternating magnetic chicanes and short undulator segments. Together with the APPLE X architecture undulators, branch can operated different modes producing FEL beams unique characteristics ranging from attosecond pulse length to high-power modes. Further space has been reserved upgrades including modulators an external seeding better timing...
Surface x-ray diffraction was used to determine the atomic structures of ${\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Sr}}_{x}{\mathrm{MnO}}_{3}$ thin films, grown monolayer by on ${\mathrm{SrTiO}}_{3}$ pulsed laser deposition. Structures for one-, two-, three-, four-, six-, and nine-monolayer-thick films were solved using Coherent Bragg rod analysis phase-retrieval method subsequent structural refinement. Four important results found. First, out-of-plane lattice constant is elongated across...
Abstract X-ray techniques have evolved over decades to become highly refined tools for a broad range of investigations. Importantly, these approaches rely on measurements that depend linearly the number incident photons. The advent free electron lasers (XFELs) is opening ability reach extremely high photon numbers within ultrashort pulse durations and leading paradigm shift in our explore nonlinear signals. However, enormous increase peak power double-edged sword with new exciting methods...
The authors present the first observation of muon spin rotation for normal (Mu) and anomalous (${\mathrm{Mu}}^{\mathrm{*}}$) muonium centers in compound semiconductors, specifically GaP GaAs. As elemental defect are characterized by a large isotropic hyperfine interaction Mu but small, highly anisotropic, 〈111〉 symmetric ${\mathrm{Mu}}^{\mathrm{*}}$. All parameters measured GaAs remarkably close to those obtained GaP. Furthermore,...
A systematic study of the behavior positive muons in orthoferrites $R{\mathrm{FeO}}_{3}$ has been performed. Measurements as a function temperature and applied magnetic field have made for $R$ = Sm, Eu, Dy, Ho, Y, Er. Typically several different sites are occupied by at low temperatures, transitions occur to one stable site with temperature-dependent rate constants. By comparing measured internal fields calculated dipolar iron ions, position muon was found be on mirror plane $m$ about 1...
Depolarization of muonium due to superhyperfine interaction, which until now has severely impeded the study in solids, can be quenched a high transverse magnetic field (1.2 T). We report observation precession single crystals KCl, Ca${\mathrm{F}}_{2}$, GaP, and ${\mathrm{Al}}_{2}$${\mathrm{O}}_{3}$. The high-field frequencies are order 2 GHz provide direct accurate (60 ppm) measure hyperfine interval. Several novel features centers observed.
We experimentally and numerically investigate the transmission of THz radiation through uniform nanoslit arrays. These structures are capable inducing plasmon-mediated field enhancement while concurrently providing high transmission. Combined with intense radiation, estimated strengths as 26 MV/cm obtained in near-field regime which will facilitate nonlinear experiments.