Surface Core-Level Photoelectron Diffraction of Surface Reconstructions

1994 ◽  
Vol 375 ◽  
Author(s):  
Eli Rotenberg ◽  
J. D. Denlinger ◽  
S. D. Kevan ◽  
B. P. Tonner
Keyword(s):  
High Energy ◽  
Core Level ◽  
High Energy Resolution ◽  
Photon Flux ◽  
Surface Geometry ◽  
Photoelectron Diffraction ◽  
Surface Reconstructions ◽  
Experimental Surface ◽  
Level Shifts ◽  
Energy Dependent

AbstractExperimental surface core-level shifts (SCLSs) aid in understanding the roles of altered electronic and screening properties at reconstructed semiconductor surfaces.1 Because of unresolved theoretical issues, the assignment of SCLSs has often remained controversial even though the surface geometry has been completely determined with traditional probes.Angular- and energy-dependent x-ray photoelectron diffraction (XPD) of each chemically resolved surface core-level electron can be used to discriminate the structure around each chemically shifted species. However, this technique requires tunability, high energy resolution to separate the SCLSs from the bulk core-levels, and high photon flux in order to gather large amounts of data in a reasonable time. Using the newly commissioned spectromicroscopy beamline 7.0 at the Advanced Light Source, we have acquired chemically-resolved XPD data for Si(111) 7×7 for several photon energies, and by examination of forward-focusing peaks we can draw tentative conclusions about the atomic origins of each core-level shifted peak.

The (1×1)→hexagonal structural transition on Pt(100) studied by high-energy resolution core level photoemission

2007 ◽  
Vol 127 (16) ◽  
pp. 164702 ◽  
Author(s):  
Alessandro Baraldi ◽  
Erik Vesselli ◽  
Laura Bianchettin ◽  
Giovanni Comelli ◽  
Silvano Lizzit ◽  
...  
Keyword(s):  
Energy Resolution ◽  
Structural Transition ◽  
High Energy ◽  
Core Level ◽  
High Energy Resolution

scholarly journals High Energy Resolution X-Ray Spectrometer for High Count Rate Xrf Applications

1993 ◽  
Vol 37 ◽  
pp. 405-411
Author(s):  
C. S. Rossington ◽  
N. W. Madden ◽  
K. Chapman
Keyword(s):  
Energy Resolution ◽  
Count Rate ◽  
High Energy ◽  
Low Noise ◽  
High Energy Resolution ◽  
Photon Flux ◽  
Large Area ◽  
High Count ◽  
High Count Rate ◽  
X Ray

AbstractA new x-ray spectrometer has been constructed which incorporates a novel large area, low capacitance Si(Li) detector and a low noise JFET (junction field effect transistor) preamplifier. The spectrometer operates at high count Tates without the conventional compromise in energy resolution. For example, at an amplifier peaking time of 1 p.sec and a throughput count rate of 145,000 counts sec-1, the energy resolution at 5.9 keV is 220 eV FWHM. Commercially available spectrometers utilizing conventional geometry Si(Li) detectors with areas equivalent to the new detector have resolutions on the order of 540 eV under the same conditions. Conventional x-ray spectrometers offering high energy resolution must employ detectors with areas one-tenth the size of the new LBL detector (20 mm2 compared with 200 mm2). However, even with the use of the smaller area detectors, the energy resolution of a commercial system is typically limited to approximately 300 eV (again, at 1 μsec and 5.9 keV) due to the noise of the commercially available JFET's. The new large area detector is useful in high count rate applications, but is also useful in the detection of weak photon signals, in which it is desirable to subtend as large an angle of the available photon flux as possible, while still maintaining excellent energy resolution. X-ray fluorescence data from die new spectrometer is shown in comparison to a commercially available system in the analysis of a dilute muhi-element material, and also in conjunction with high count rate synchrotron EXAFS applications.

X-ray diffractometer for the investigation of temperature- and magnetic field-induced structural phase transitions

2018 ◽  
Vol 51 (3) ◽  
pp. 761-767 ◽  
Author(s):  
Tom Faske ◽  
Wolfgang Donner
Keyword(s):  
Phase Transitions ◽  
Energy Resolution ◽  
Structural Phase ◽  
High Energy ◽  
High Energy Resolution ◽  
Photon Flux ◽  
Structural Phase Transitions ◽  
X Ray ◽  
And Performance

This article reports the development and characterization of a laboratory-based high-resolution X-ray powder diffractometer equipped with a 5.5 T magnet and closed-cycle helium cryostat that is primarily designed for the investigation of magneto-structural phase transitions. Unique features of the diffractometer include the position-sensitive detector, allowing the collection of an entire diffraction pattern at once, and the high energy resolution with Mo Kα 1 radiation. The ability to utilize a lower energy resolution but higher photon flux by switching to an X-ray mirror monochromator makes it a versatile setup for a variety of compounds. In this contribution, details of the design and performance of the instrument are presented along with its specifications.

scholarly journals The PM3 beamline at BESSY II

2016 ◽  
Vol 2 ◽  
Author(s):  
Torsten Kachel
Keyword(s):  
Circular Polarization ◽  
Energy Resolution ◽  
High Stability ◽  
High Energy ◽  
High Energy Resolution ◽  
Photon Flux ◽  
High Photon Flux ◽  
Elliptically Polarized

<p>PM3 merges the developments of the former BESSY I SX700 III monochromator for elliptically polarized VUV radiation and of BESSY II collimated plane grating monochromators. This way it is possible to achieve circular polarization from a BESSY II dipole in the range 20 – 2000 eV with high photon flux, high energy resolution and high stability.</p>

scholarly journals High-Resolution Core-Level Photoabsorption of Alkali Halides

1993 ◽  
Vol 307 ◽  
Author(s):  
E. Hudson ◽  
E. Moler ◽  
Y. Zheng ◽  
S. Kellar ◽  
P. Heimann ◽  
...  
Keyword(s):  
Alkali Halides ◽  
High Energy ◽  
Core Level ◽  
High Energy Resolution ◽  
X Rays ◽  
Edge Structure ◽  
Photoabsorption Spectrum ◽  
Halide Salts ◽  
X Ray Absorption ◽  
Absorption Features

ABSTRACTThe X-ray Absorption Near Edge Structure (XANES) of single-crystal alkali halide salts have been measured at low temperature (T≈80 K). By employing the electron partial-yield detection technique, spectra of NaF, NaCI, and NaBr were obtained near the sodium K-edge and spectra of LiF, NaF, and KF were obtained near the fluorine K-edge. All spectra showed sharp features at the absorption threshold and broader absorption features extending 50–80 eV above threshold. The high energy resolution of the soft X-rays (ΔE/E ≈ 4000) allowed the detection of previously unobserved fine structure, particularly in the near-edge region. The narrow features below and just above threshold are attributed to core-level excitons. The intense, broader peaks further above threshold are assigned to single-electron scattering resonances. An ab initio multiple-scattering calculation is used to model the latter effect. Contributions from atomic multielectron excitations, estimated by a comparison to the K-edge photoabsorption spectrum of Ne in the gas phase, are found to be very small.

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