Incident photon energy dependence of the resonant x-ray magnetic scattering cross section of a samarium film

2002 ◽  
Vol 65 (6) ◽  
Author(s):  
A. Stunault ◽  
K. Dumesnil ◽  
C. Dufour ◽  
C. Vettier ◽  
N. Bernhoeft
1997 ◽  
Vol 40 (5) ◽  
pp. 569-574 ◽  
Author(s):  
J Strempfer ◽  
Th Brückel ◽  
D Hupfeld ◽  
J. R Schneider ◽  
K.-D Liss ◽  
...  

2001 ◽  
Vol 678 ◽  
Author(s):  
C.S. Nelson ◽  
Y.J. Kim ◽  
J.P. Hill ◽  
Doon Gibbs ◽  
V. Kiryukhin ◽  
...  

AbstractWe report x-ray scattering studies of polarons and tilt ordering in the high-temperature, paramagnetic insulating phase of La0.7Ca0.3MnO3. The temperature dependence of scattering due to individual and correlated polarons was measured, and the latter was found to disappear at ∼400 K. The scattering due to tilt ordering, which was observed by tuning the incident photon energy near the La L1 edge, was also measured as a function of temperature. The destruction of tilt ordering at ∼690 K is believed to be associated with the orthorhombic-rhombohedral structural transition.


2019 ◽  
Vol 32 (3) ◽  
pp. 323-330
Author(s):  
Vinay Venugopal ◽  
Piyush S. Bhagdikar

Here, we consider the problem of separating the relative contributions of kinematics and dynamics to the differential Klein‐Nishina electronic cross section using graphical and numerical analysis. We show that the values of the energy of scattered photons, and hence the kinetic energy of recoiled electrons calculated from Compton's quantum theory of scattering of radiation, show a degree of matching that increases with the increase in incident photon energy as quantified by chi-square goodness of fit test, with the calculated differential Klein‐Nishina electronic cross section per electron per unit solid angle for the scattering of an unpolarized photon by a stationary free electron, when appropriate normalization procedures are invoked. There is a high degree of matching in a regime where the total electronic Klein‐Nishina cross section for the Compton scattering on a free stationary electron scales as the inverse of the incident photon energy and the contribution of the electro-magnetic interaction to differential electronic cross section diminishes. Hence the third level explanation of Compton effect by quantum electrodynamics has a degree of matching with the first level of Compton's quantum theory. The degree of mismatch is an indicator of the relative contribution of dynamics to differential Klein‐Nishina electronic cross section compared to kinematics. For incident photon energies less than 1 MeV, we obtain the values of the scattering angles at which calculated differential cross section is nonzero but is kinematically limited which may lead to broadening of Compton profile. At the scattering angle where the differential cross section value is minimum for a given incident photon energy, we obtain the relative contribution of dynamics to the differential cross section compared to kinematics. Therefore, these predictions which need to be confirmed experimentally have significance to the understanding of the mechanisms of photon‐electron interactions in the Compton scattering.


1990 ◽  
Vol 68 (11) ◽  
pp. 1279-1290
Author(s):  
W. Mayr ◽  
G. Fritsch ◽  
E. Lüscher

We report on experimental results for the thermal diffuse X-ray-scattering cross section from Na single crystals. Data are presented for the [100], [110], and [111] directions taken in the temperature range from 38 K to the melting point. In addition we present a numerical calculation of the harmonic diffuse-scattering cross section including all orders of multiphonon contributions using a realistic phonon-dispersion relation. The results of this model are compared with a simpler approximation for the higher order multiphonon terms. The differences between the calculations and the experimental data show a distinct asymmetrical behaviour with respect to the reciprocal lattice points. Owing to this fact and their temperature dependence they can be related to anharmonic scattering. The contributions of the four lowest order terms are derived from the data. The lowest order antisymmetric contribution agrees quite well with available theoretical calculations.


2014 ◽  
Vol 21 (4) ◽  
pp. 736-743 ◽  
Author(s):  
Tony Warwick ◽  
Yi-De Chuang ◽  
Dmitriy L. Voronov ◽  
Howard A. Padmore

The optical design of a two-dimensional imaging soft X-ray spectrometer is described. A monochromator will produce a dispersed spectrum in a narrow vertical illuminated stripe (∼2 µm wide by ∼2 mm tall) on a sample. The spectrometer will use inelastically scattered X-rays to image the extended field on the sample in the incident photon energy direction (vertical), resolving the incident photon energy. At the same time it will image and disperse the scattered photons in the orthogonal (horizontal) direction, resolving the scattered photon energy. The principal challenge is to design a system that images from the flat-field illumination of the sample to the flat field of the detector and to achieve sufficiently high spectral resolution. This spectrometer provides a completely parallel resonant inelastic X-ray scattering measurement at high spectral resolution (∼30000) over the energy bandwidth (∼5 eV) of a soft X-ray absorption resonance.


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