scholarly journals Magnetic X-Ray Circular Dichroism in Spin-Polarized Photoelectron Diffraction

1994 ◽  
Vol 375 ◽  
Author(s):  
G. D. Waddill ◽  
J. G. Tobin ◽  
X. Guo ◽  
S. Y. Tong
Keyword(s):  
Magnetic Structure ◽  
Multiple Scattering ◽  
Analytical Procedure ◽  
Structural Determination ◽  
X Rays ◽  
Circularly Polarized ◽  
X Ray ◽  
Photoelectron Diffraction ◽  
Spin Polarized ◽  
Energy Dependent

AbstractThe first structural determination with spin-polarized, energy-dependent photoelectron diffraction using circularly-polarized x-rays is reported for Fe films on Cu(001). Circularly-polarized x-rays produce spin-polarized photoelectrons from the Fe 2p doublet, and intensity asymmetries in the 2p3/2 level are observed. Fully spin-specific multiple scattering calculations reproduce the experimentally-determined energy and angular dependences. A new analytical procedure which focuses upon intensity variations due to spin-dependent diffraction is introduced. A sensitivity to local geometric and magnetic structure is demonstrated.

Spin-polarized photoelectron diffraction using circularly polarized x rays

1994 ◽  
Vol 50 (10) ◽  
pp. 6774-6778 ◽  
Author(s):  
G. D. Waddill ◽  
J. G. Tobin ◽  
X. Guo ◽  
S. Y. Tong
Keyword(s):  
X Rays ◽  
Circularly Polarized ◽  
Photoelectron Diffraction ◽  
Spin Polarized

scholarly journals Multiple Scattering Theory of Spin-Polarized X-ray Photoelectron Diffraction

2005 ◽  
Vol 3 ◽  
pp. 353-357 ◽  
Author(s):  
Kouta Ito ◽  
Hiroshi Shinotsuka ◽  
Takehisa Konishi ◽  
Takashi Fujikawa
Keyword(s):  
Multiple Scattering ◽  
Scattering Theory ◽  
Multiple Scattering Theory ◽  
X Ray ◽  
Photoelectron Diffraction ◽  
Spin Polarized

scholarly journals Nested Kirkpatrick–Baez (Montel) optics for hard X-rays

2015 ◽  
Vol 48 (2) ◽  
pp. 558-564 ◽  
Author(s):  
Giacomo Resta ◽  
Boris Khaykovich ◽  
David Moncton
Keyword(s):  
Ray Tracing ◽  
Compton Scattering ◽  
Analytical Procedure ◽  
X Rays ◽  
Multilayer Mirrors ◽  
Comprehensive Description ◽  
X Ray ◽  
Inverse Compton Scattering ◽  
Inverse Compton ◽  
Proper Orientation

A comprehensive description and ray-tracing simulations are presented for symmetric nested Kirkpatrick–Baez (KB) mirrors, commonly used at synchrotrons and in commercial X-ray sources. This paper introduces an analytical procedure for determining the proper orientation between the two surfaces composing the nested KB optics. This procedure has been used to design and simulate collimating optics for a hard-X-ray inverse Compton scattering source. The resulting optical device is composed of two 12 cm-long parabolic surfaces coated with a laterally graded multilayer and is capable of collimating a 12 keV beam with a divergence of 5 mrad (FWHM) by a factor of ∼250. A description of the ray-tracing software that was developed to simulate the graded multilayer mirrors is included.

scholarly journals Three dimensions, two microscopes, one code: Automatic differentiation for x-ray nanotomography beyond the depth of focus limit

2020 ◽  
Vol 6 (13) ◽  
pp. eaay3700 ◽  
Author(s):  
Ming Du ◽  
Youssef S. G. Nashed ◽  
Saugat Kandel ◽  
Doğa Gürsoy ◽  
Chris Jacobsen
Keyword(s):  
Multiple Scattering ◽  
Automatic Differentiation ◽  
Optimization Problems ◽  
Three Dimensions ◽  
Reconstruction Method ◽  
X Rays ◽  
Reconstruction Algorithms ◽  
Depth Of Focus ◽  
X Ray ◽  
Diffraction Effects

Conventional tomographic reconstruction algorithms assume that one has obtained pure projection images, involving no within-specimen diffraction effects nor multiple scattering. Advances in x-ray nanotomography are leading toward the violation of these assumptions, by combining the high penetration power of x-rays, which enables thick specimens to be imaged, with improved spatial resolution that decreases the depth of focus of the imaging system. We describe a reconstruction method where multiple scattering and diffraction effects in thick samples are modeled by multislice propagation and the 3D object function is retrieved through iterative optimization. We show that the same proposed method works for both full-field microscopy and for coherent scanning techniques like ptychography. Our implementation uses the optimization toolbox and the automatic differentiation capability of the open-source deep learning package TensorFlow, demonstrating a straightforward way to solve optimization problems in computational imaging with flexibility and portability.

STRUCTURAL DETERMINATION OF THE Si/Cu(110) INTERFACE BY PHOTOELECTRON DIFFRACTION

1997 ◽  
Vol 04 (06) ◽  
pp. 1331-1335 ◽  
Author(s):  
C. ROJAS ◽  
J. A. MARTÍn-GAGO ◽  
E. ROMÁN ◽  
G. PAOLUCCI ◽  
B. BRENA ◽  
...  
Keyword(s):  
Room Temperature ◽  
Structural Parameters ◽  
Single Scattering ◽  
Structural Determination ◽  
X Ray ◽  
Photoelectron Diffraction ◽  
First Order ◽  
Proposed Model ◽  
Laboratory Source

Deposition of 0.5 Si monolayer (ML) on a Cu (110) surface at room temperature (RT) leads to the formation of a c(2×2) LEED pattern. In order to find out the surface atomic structure of this ordered phase, X-ray photoelectron diffraction (XPD) azimuthal scans at different photon energies and full hemispherical XPD patterns of the Si 2 p core level have been measured using both synchrotron radiation and a laboratory source. We present an atomic model for the surface structure based on the examination of forward scattering and first order interference XPD features. Refinement of the structural parameters was achieved by performing single scattering cluster (SSC) calculations. In the proposed model Si atoms replace Cu atoms at the surface along the [Formula: see text] atomic rows.

Absorption and secondary scattering of X-rays with an off-axis small beam for a cylindrical sample geometry

2019 ◽  
Vol 75 (2) ◽  
pp. 362-369
Author(s):  
Daniel C. Van Hoesen ◽  
James C. Bendert ◽  
Kenneth F. Kelton
Keyword(s):  
Multiple Scattering ◽  
Incident Beam ◽  
Cylindrical Sample ◽  
X Rays ◽  
Beam Size ◽  
X Ray ◽  
Sample Geometry ◽  
Integral Forms ◽  
Secondary Scattering ◽  
X Ray Absorption

Expressions for X-ray absorption and secondary scattering are developed for cylindrical sample geometries. The incident-beam size is assumed to be smaller than the sample and in general directed off-axis onto the cylindrical sample. It is shown that an offset beam has a non-negligible effect on both the absorption and multiple scattering terms, resulting in an asymmetric correction that must be applied to the measured scattering intensities. The integral forms of the corrections are first presented. A small-beam limit is then developed for easier computation.

MAGNETIC DICHROISM UNDER EXCITATION BY UNPOLARIZED RADIATION

1997 ◽  
Vol 04 (05) ◽  
pp. 919-922 ◽  
Author(s):  
A. FANELSA ◽  
R. SCHELLENBERG ◽  
F. U. HILLEBRECHT ◽  
E. KISKER
Keyword(s):  
Angular Distribution ◽  
Geometric Structure ◽  
Photoelectron Spectroscopy ◽  
Emission Angle ◽  
X Rays ◽  
Strong Variation ◽  
X Ray ◽  
Photoelectron Diffraction ◽  
Magnetic Dichroism ◽  
Unpolarized Radiation

Magnetic dichroism has been observed in the angular distribution of p-core level photoemission spectra excited from crystalline ferromagnets by unpolarized X-rays. The angular dependence of the angular and energy-resolved photoemission intensity was recorded as a function of the emission direction with respect to the crystal, revealing a strong variation of the magnetic dichroism with emission angle due to photoelectron diffraction. This variation is particularly strong around the forward scattering peaks, including sign reversals close to these directions. The results demonstrate that any standard X-ray photoelectron spectroscopy apparatus possesses the potential for combined analysis of surface magnetic structure and geometric structure in a chemically specific way.

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