Synchrotron measurements

The 2s partial ionization cross section for neon has been studied from threshold out to about 130 eV by Codling et al.131 using synchrotron radiation and two types of photoelectron spectrometer (127° and CMA). The results are more closely represented by R-matrix,128 or RPAE,55 theory than by the Hartree-Fock calculations.132 Wuilleumier and Krause137 have studied Ne(2s) ionization with a few soft-X-ray lines, and these results, together with a single measurement near threshold by Samson and Gardner136 are compatible with the synchrotron measurements.131... 

As in any diffraction study, three kinds of information can in principle be derived from such experiments (1) the spacing of the diffracting planes from the diffraction peak positions, (2) the translational correlation length from the peak width, and (3) the structure factors from the integrated peak intensity. In a typical synchrotron measurement, the primary beam is defined by a slit 2mm wide and 70mm high. Since the angle of incidence is of the order of... 

Fogarassy, P., Cofino, B., Millet, P., and Lodini, A. (2005) Residual stress in hydroxyapatite coating nonlinear analysis and high energy synchrotron measurements. IEEE Trans. Biomed. Eng., 22 (7), 1161-1166. 

Another important contribution of electron microscopy is to assist chemists in the development of new superconducting compounds by identifying the phases produced and to correlate the results with the synthesis conditions. When attempts were made to produce Hg-containing compounds using different precursors, Tc always tended to be much lower (69 K for the Hg-1223 phase while the Hg-1234 phase does not superconduct) [7.74]. X-ray synchrotron measurements on powder material revealed a large deficiency on the Hg site. 

Fig. 19.10 Changes in internal stress of a Scandia stabilized zirconia electrolyte and NiO-YSZ anode as determined by in situ synchrotron measurements. (Reproduced with permissions Sumi et al. J Fuel cell Sci Tech)...

The assistance from Dr. F. J. Yeh, Dr. Z. G. Wang, S. Kim and J. L. Lopez during synchrotron measurements is gratefully acknowledged. The financial support of this project is by a grant from the National Science Foundation (DMR 9732653). 

Finally, the crystal structures of P-4b and Pigment Blue 80 were fitted to the experimental powder diagrams by Rietveld refinements. For Pigment Blue 80 high-resolution powder data from synchrotron measurements were used. (For P-4b synchrotron measurements do not make sense, since the low quality of the powder diagram is caused by the low crystallinity of the samples, not by the diffractometer.) Details on the lattice energy minimizations and Rietveld refinement of 4b are given in Ref [20]. 

This work was performed under the auspices of the U. S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under Contract No. W-7405-Eng-48. The author would like to thank J. W. Elmer, E.M. Larson, M. Froeba, T. Ressler, T, Palmer, P.A. Waide and A. Teruya for their collaboration and technical support in the course of developing these synehrotron tools for welding metallurgy. Synchrotron measurements were performed at Stanford Synchrotron Radiation Laboratory, supported by US Department of Energy, Office of Basic Energy Sciences. 

Ultraviolet photoelectron spectroscopy (UPS) is a variety of photoelectron spectroscopy that is aimed at measuring the valence band, as described in sectionBl.25.2.3. Valence band spectroscopy is best perfonned with photon energies in the range of 20-50 eV. A He discharge lamp, which can produce 21.2 or 40.8 eV photons, is commonly used as the excitation source m the laboratory, or UPS can be perfonned with synchrotron radiation. Note that UPS is sometimes just referred to as photoelectron spectroscopy (PES), or simply valence band photoemission. 

The analysis was performed by XRF method with SR. SRXRF is an instrumental, multielemental, non-destructive analytical method using synchrotron radiation as primary excitation source. The fluorescence radiation was measured on the XRF beam-line of VEPP-3 (E=2 GeV, 1=100 mA), Institute of Nuclear Physics, Novosibirsk, Russia. For quality control were used international reference standards. 

XRD offers unparalleled accuracy in the measurement of atomic spacings and is the technique of choice for determining strain states in thin films. XRD is noncontact and nondestructive, which makes it ideal for in situ studies. The intensities measured with XRD can provide quantitative, accurate information on the atomic arrangements at interfaces (e.g., in multilayers). Materials composed of any element can be successfully studied with XRD, but XRD is most sensitive to high-Z elements, since the diffracted intensity from these is much lar r than from low-Z elements. As a consequence, the sensitivity of XRD depends on the material of interest. With lab-based equipment, surface sensitivities down to a thickness of -50 A are achievable, but synchrotron radiation (because of its higher intensity)... 

XRD is an excellenr, nondestructive method for identifying phases and characterizing the structural properties of thin films and multilayers. It is inexpensive and easy to implement. The future will see more use of GIXD and depth dependent measurements, since these provide important information and can be carried out on lab-based equipment (rather than requiring synchrotron radiation). Position sensitive detectors will continue to replace counters and photographic film. 

The discovery of the phenomenon that is now known as extended X-ray absorption fine structure (EXAFS) was made in the 1920s, however, it wasn t until the 1970s that two developments set the foundation for the theory and practice of EXAFS measurements. The first was the demonstration of mathematical algorithms for the analysis of EXAFS data. The second was the advent of intense synchrotron radiation of X-ray wavelengths that immensely facilitated the acquisition of these data. During the past two decades, the use of EXAFS has become firmly established as a practical and powerfiil analytical capability for structure determination. ... 

The only X-ray source with sufficient intensity for surface measurements is synchrotron radiation. Synchrotron radiation is white light, including all wavelengths ftom the infrared to X rays. A spectroscopy experiment needs a particular wavelength (photon energy) to be selected with a monochromator and scanned through... 

In both cases, laboratory X-ray sources may be used and the X-ray measurements taken in 0-29 geometry. For weakly scattering systems synchrotron radiation is helpful. 

Both techniques use a very high flux X-rays synchrotron radiation is needed for this kind of measurements. 

The method involves the irradiation of a sample with polychromatic X-rays (synchrotron radiation) which inter alia promote electrons from the innermost Is level of the sulfur atom to the lowest unoccupied molecular orbitals. In the present case these are the S-S antibonding ct -MOs. The intensity of the absorption lines resulting from these electronic excitations are proportional to the number of such bonds in the molecule. Therefore, the spectra of sulfur compounds show significant differences in the positions and/or the relative intensities of the absorption lines [215, 220, 221]. In principle, solid, liquid and gaseous samples can be measured. 

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