A5067097713- Electron and X-Ray Spectroscopy Techniques
- Advanced X-ray Imaging Techniques
- Particle Accelerators and Free-Electron Lasers
- X-ray Spectroscopy and Fluorescence Analysis
- Advanced Chemical Physics Studies
- Surface and Thin Film Phenomena
- Advanced Electron Microscopy Techniques and Applications
- Particle accelerators and beam dynamics
- Magnetic properties of thin films
- Physics of Superconductivity and Magnetism
- Photocathodes and Microchannel Plates
- Superconducting Materials and Applications
- Semiconductor materials and devices
- Inorganic Fluorides and Related Compounds
- Advancements in Photolithography Techniques
- Electronic and Structural Properties of Oxides
- Optical Coatings and Gratings
- Crystallography and Radiation Phenomena
- Nuclear Physics and Applications
- Molecular Junctions and Nanostructures
- Advanced Surface Polishing Techniques
- X-ray Diffraction in Crystallography
- Machine Learning in Materials Science
- Quantum and electron transport phenomena
- Photonic and Optical Devices
Brookhaven National Laboratory
2009-2025
National Synchrotron Light Source II
2007-2009
Stony Brook University
1992-2007
Stanford Synchrotron Radiation Lightsource
2007
RIKEN BNL Research Center
2004-2006
Argonne National Laboratory
1996
State University of New York
1996
North Carolina State University
1996
King's College London
1996
Lawrence Berkeley National Laboratory
1996
Over the past decades, superconducting qubits have emerged as one of leading hardware platforms for realizing a quantum processor. Consequently, researchers made significant effort to understand loss channels that limit coherence times qubits. A major source has been attributed two level systems are present at material interfaces. It is recently shown replacing metal in capacitor transmon with tantalum yields record relaxation and qubits, motivating detailed study surface. In this work,...
Dichroic interference effects were observed in circularly polarized soft-x-ray reflectivity at the Co ${\mathit{L}}_{2,3}$ edges of a magnetic multilayer. The data show maximum asymmetry ratio 80%, greater than degree circular polarization incident light, changeover dichroic characteristics with increasing grazing angle, and an inverted pattern angular dependence ratio. These observations are explained successfully by classical electromagnetic model calculation which includes complete state...
The scanning photoelectron microscope at the National Synchrotron Light Source (NSLS) has recently recorded micrographs with a resolution below half micron. To demonstrate elemental and chemical sensitivity submicron level, an artificial structure consisting of Al SiO2 lines on boron-doped silicon substrate was examined. 2p Si primary photoelectrons as well O KVV Auger electrons were used for image formation. Contrast reversal between areas observed in images formed from oxide-shifted...
We present photoemission spectra from the $3p$ level of Cu(100) obtained in coincidence with ${M}_{3}\mathrm{VV}$ Auger line. The is narrowed its 2.2-eV core-lifetime-broadened width to 1.0 eV, representing intrinsic $^{1}G$ final state. core line changes energy within envelope as changed, conserving sum Auger-electron and photoelectron kinetic energies.
Abstract Despite constituting a smaller fraction of the qubit's electromagnetic mode, surfaces and interfaces can exert significant influence as sources high‐loss tangents, which brings forward need to reveal properties these extended defects identify routes their control. Here, we examine structure composition metal‐substrate interfacial layer that exists in Ta/sapphire‐based superconducting films. Synchrotron‐based X‐ray reflectivity measurements Ta films, commonly used qubits, an...
We demonstrate that it is possible to obtain spin-resolved valence band spectra with a very high degree of spin polarization from antiferromagnetic transition metal materials if the excitation light circularly polarized and has an energy close cation ${2p}_{3/2}$ ( ${L}_{3}$) white line. are able unravel different states in single-particle spectrum CuO show top pure singlet character, which provides strong support for existence stability Zhang-Rice singlets high- ${T}_{c}$ superconductors.
The technique of Auger photoelectron coincidence spectroscopy (APECS) using synchrotron radiation is discussed. Technical considerations and experimental details are emphasized. Results from Cu(100), Ta(100), Al(111) presented to show the kinds new information that APECS can provide.
A beamline has been established at the National Synchrotron Light Source to perform angle-resolved photoemission experiments on magnetic surfaces with spin sensitivity. The system two novel features: it uses a miniature electron-spin polarization analyzer and also synchrotron radiation from an undulator rather than bending magnet.
Abstract Scaling up superconducting quantum circuits based on transmon qubits necessitates substantial enhancements in qubit coherence time. Over recent years, tantalum (Ta) has emerged as a promising candidate for qubits, surpassing conventional counterparts terms of However, amorphous surface Ta oxide layer may introduce dielectric loss, ultimately placing limit the In this study, novel approach suppressing formation using an ultrathin magnesium (Mg) capping is presented. Synchrotron‐based...
We report the formation of heteroepitaxial copper phthalocyanine (CuPc) overlayers on a “5×20” reconstructed Au(001) substrate, with thicknesses ranging from 0.8 to 26.9 Å. The adsorbed CuPc at room temperature forms quasiepitaxial overlayer, incommensurate substrate lattice, aligned 〈110〉 and 〈11̄0〉 axes surface. At elevated temperatures (ET) between 200 250 °C, deposition results in 13.8 Å square overlayer structure commensurate lattice. electronic structures grown both RT ET are also...
The X1A soft X-ray undulator beamline at the NSLS has been rebuilt to serve two microscopy stations operating simultaneously. Separate spherical-grating monochromators provide resolving power required for XANES spectroscopy C, N and O absorption edges. exit slits are fixed define coherent source experiments. optical design operational performance described.
Thin films of metallophthalocyanine (MPc,M=Co,Ni) evaporated onto a “5×20” reconstructed Au(001) substrate at room temperature have been investigated by employing low energy electron diffraction (LEED) and ultraviolet photoelectron spectroscopy (UPS). The LEED images from NiPc thin show that the overlayers are highly ordered with square unit cell 12.8×12.8Å2 aligned along ⟨110⟩ ⟨11¯0⟩ axes substrate. For CoPc, pattern reveals superposition multiple rotationally equivalent domains 12.9×12.9Å2...
Tunable and polarized soft x-ray radiation was used to excite core electrons of H2O. Angle-resolved proton yields were measured by retarding potential analyzers at 0° 90° with respect the polarization vector radiation. The ability angle-resolved detection reveal hidden resonances in rich molecular spectra is demonstrated, anisotropy parameter obtained from two ion identifies symmetries relative oscillator strengths core-hole excited states near-edge region spectrum. analysis data...
Views Icon Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Twitter Facebook Reddit LinkedIn Tools Reprints and Permissions Cite Search Site Citation H. Ade, J. Kirz, S. Hulbert, E. Johnson, Anderson, D. Kern; Images of a microelectronic device with the X1‐SPEM, first generation scanning photoemission microscope at National Synchrotron Light Source. Vac. Sci. Technol. A 1 May 1991; 9 (3): 1902–1906. https://doi.org/10.1116/1.577541 Download citation file:...
Core-valence-valence (CVV) Auger spectra from Ta(100) taken in coincidence with bulk and surface-shifted 4${\mathit{f}}_{7/2}$ core-level emission are presented. These data compared self-convolutions of calculations the d-band densities states for surface subsurface layers a nine-layer slab. Agreement spectrum calculation is good; agreement very poor. explained by proposing an interatomic to decay mode core hole that competitive conventional CVV process.
We have been developing an instrument that combines the techniques of x-ray photoelectron spectroscopy and zone plate microfocusing to perform spectromicroscopy. The X1A undulator provides a bright photon source in soft range with high degree spatial coherence (a requirement for focusing). A spherical grating monochromator selects desired energy 280–800 eV range. Fresnel focuses beam small spot. Photoelectron spectra can be acquired from irradiated area electron analyzer. With focused on...
The Ta ${\mathit{N}}_{7}$-VV Auger spectrum of TaC(111) has been measured in coincidence with photoemission from the bulk and surface shifted 4${\mathit{f}}_{7/2}$ core levels. Good agreement is found between a self-convolution density states (SCDOS) at sites determined by first-principles calculation. disagrees SCDOS but well described an incoherent sum spectrum. A novel off-site decay mechanism, first observed on Ta(100), accounts for these observations.
The basic principles and practical considerations of Auger-Photoelectron Coincidence Spectroscopy (APECS) are discussed. In this technique, core photoelectrons their associated Auger elecrtons detected in time coincidence. For true coincidence counts, both electrons originate from the same photoexcitation event enabling one to prove local electronic structure excitation phenomena with unprecedented discrimination. Originally developed by Haak, Sawatzky Thomas [1, 2] using a conventional...
We present Auger–photoelectron coincidence spectra from the stoichiometric and reduced (by vacuum annealing) TiO2(110) surfaces after saturation exposure to NH3 at room temperature. The Ti 3p photoemission spectrum shows substantial emission residual (or intrinsic) defects on surface additional thermally-induced bridging oxygen vacancies surface. Changes in line shape of upon adsorption show that binds five-fold coordinated ions rosette structures both surfaces, surface, but not intrinsic...
Al ${\mathit{L}}_{2,3}$VV auger-photoelectron coincidence (APEC) data are presented and discussed. The well-known ability of APEC to suppress inelastic-scattering contributions Auger photoelectron spectra is used demonstrate that much the large low-energy tail common core-valence-valence from many wide-band solids not due secondary-electron scattering, but, rather, an intrinsic part core-hole-decay process.
We present high resolution Ag ${M}_{5}\mathrm{VV}$ and ${M}_{4}\mathrm{VV}$ Auger spectra obtained in coincidence with ${3d}_{5/2}$ ${3d}_{3/2}$ core photoelectrons, respectively. photoelectron spectroscopy (APECS) was used to separate these overlapping lines determine the intrinsic line shape of each spectrum. As on-site Coulomb correlation energy U is comparable twice $4d$ bandwidth, $2W,$ (i.e., $U/2W\ensuremath{\sim}1),$ exhibit both atomiclike bandlike character. find that whether...