Calculation of scattering curves for macromolecules in solution and comparison with results of methods using effective atomic scattering factors

1983 ◽  
Vol 16 (1) ◽  
pp. 74-82 ◽  
Author(s):  
J. J. Müller
Keyword(s):  
Scattering Data ◽  
Structure Parameters ◽  
Wide Angle ◽  
X Ray ◽  
Rna Molecules ◽  
Dna And Rna ◽  
X Ray Scattering ◽  
Atomic Scattering Factor ◽  
Atomic Scattering ◽  
Scattering Factor

An improved cube method was developed for the computation of X-ray scattering curves of macromolecules in solution. For double-helical DNA and RNA molecules the efficiency of this method is shown. The results are compared with curves calculated by effective atomic scattering factor methods. In the small-angle and in the wide-angle regions the improved cube method is superior to the effective atomic scattering factor methods. This was proved by the calculation of structure parameters and by a comparison with experimental scattering data. On the basis of the improved cube method, models with a reduced structure resolution are deduced for DNA and RNA molecules. The models consisting of the three scattering centres phosphate, sugar and base per nucleotide are equivalent in scattering to the real structure up to a scattering angle of about 0.15 rad for copper radiation.

scholarly journals Calculation of The Imaginary Part of Atomic Form Factor For X-ray In Nickel

2019 ◽  
Vol 23 (10) ◽  
pp. 66
Author(s):  
Ahmed Raheem Ahmed ◽  
, Muhsin Hasan Ali
Keyword(s):  
Imaginary Part ◽  
High Energy ◽  
Approximate Methods ◽  
X Ray ◽  
X Ray Scattering ◽  
Atomic Scattering Factor ◽  
Atomic Scattering ◽  
Scattering Factor ◽  
Atomic Form Factor ◽  
Good Agreement

In the present study, we calculated the imaginary part of the x-ray scattering factor of nickel based on the principles of quantum mechanics to find a wave function that describes the electronic state of atoms by approximate methods, observed the study suggested that in both low energy values , and at high energy values , the imaginary part is approximately zero, this means that the electrons are intensely connected to the atom, where in the spectrum the photon energies are approximately equal to the electron bonding energy  we note the study pointed out that the imaginary part of the atomic scattering factor become  prominent and the electron becomes highly absorbent, the relative accuracy varies within range (0.03-0.22)%, and there was also a good agreement between the behavior we obtained for the imaginary part of the atomic scattering factor and the behavior that was calculated using other models.    http://dx.doi.org/10.25130/tjps.23.2018.171

scholarly journals Coherent X-ray Scattering by Co III

1985 ◽  
Vol 38 (4) ◽  
pp. 609
Author(s):  
R Glass
Keyword(s):  
Ground State ◽  
Open Shell ◽  
Sufficient Accuracy ◽  
X Ray ◽  
Hartree Fock ◽  
X Ray Scattering ◽  
Atomic Scattering Factor ◽  
Atomic Scattering ◽  
Scattering Factor ◽  
State Configuration

The atomic scattering factor for the ground state of the cobalt ion, 3d7 4F, has been evaluated using nonrelativistic and 'relativistic-corrected' wavefunctions of varying accuracy. The importance of incorporating all types of electron correlation systematically within the valence subshell while keeping a fixed argon core is discussed. From the results presented, it appears that atomic scattering factors evaluated using Hartree-Fock wavefunctions are of sufficient accuracy for an atomic ion with an open-shell ground-state configuration.

X-Ray Determination of Site Occupation Parameters in Ordered Ternaries Cu(Aux.M1x.)M = Ni,Pd

1990 ◽  
Vol 213 ◽  
Author(s):  
R. Kumar ◽  
C. J. Sparks ◽  
T. Shiraishi ◽  
E.D. Specht ◽  
P. Zschack ◽  
...  
Keyword(s):  
Rietveld Method ◽  
Scattering Data ◽  
X Rays ◽  
X Ray ◽  
Site Occupation ◽  
Intensity Measurements ◽  
X Ray Scattering ◽  
Chemical Phase ◽  
Multiple Wavelengths ◽  
Scattering Factor

ABSTRACTX-ray scattering data obtained for multiple wavelengths with synchrotron radiation were analyzed by the Rietveld method to determine Ni and Pd distributions on the Cu(000) and Au(½½½) sites in the CuAuI tetragonal P4/mmm structure. Alloys of CuAuxM1-x containing 6 at. % Ni or 10 and 25 at. % Pd were processed to obtain maximum ordering. Nickel is predominantly found on the Cu site and most all the Pd is found on the Au site. The uncertainty in site occupation parameters is discussed for various contributions which affect powder intensity measurements. For highly absorbing materials, an observed powder roughness effect decreases the low angle (2θ) intensities relative to the high 2θ intensities. This effect reduces the reliability of the thermal parameters and obscures a proper description of the thermal motion of the two sublattices. Corrections to the X-ray intensity data for surface roughness/porosity effects reduce uncertainties to about ±1 at. % on the refined value of the site occupations. This use of variable wavelength X-rays with simultaneous refinement of the corresponding data is capable of distinguishing site occupations even between two elements of almost equal scattering factor as, for example, Cu and Ni atoms in this investigation. Chemical phase stability is related to the site occupation parameters.

Anomalous x-ray atomic scattering factor for Zr, Nb, and Mo

1989 ◽  
Vol 40 (9) ◽  
pp. 5420-5421
Author(s):  
M. S. Wang ◽  
Sheau-Huey Chia
Keyword(s):  
X Ray ◽  
Atomic Scattering Factor ◽  
Atomic Scattering ◽  
Scattering Factor

In-house simultaneous collection of small-angle X-ray scattering, wide-angle X-ray diffraction and Raman scattering data from polymeric materials

2014 ◽  
Vol 47 (3) ◽  
pp. 922-930 ◽  
Author(s):  
Raita Hirose ◽  
Taiyo Yoshioka ◽  
Hiroko Yamamoto ◽  
Kummetha Raghunatha Reddy ◽  
Daisuke Tahara ◽  
...  
Keyword(s):  
Raman Scattering ◽  
Small Angle ◽  
Polymeric Materials ◽  
Scattering Data ◽  
Present System ◽  
Wide Angle ◽  
X Ray Diffraction ◽  
X Ray ◽  
X Ray Scattering ◽  
Ray Scattering

An in-house X-ray scattering system, which can simultaneously measure small-angle X-ray scattering (SAXS) and wide-angle X-ray diffraction (WAXD) data, as well Raman scattering data, has been developed to study the phase transitions of polymeric materials. To date, these types of measurements have been limited to synchrotron radiation. The present system is an in-house SAXS system combined with a WAXD detector and a Raman spectrometer. A rotating-anode X-ray generator and multilayer optic are employed to provide a high-flux X-ray beam. Two two-dimensional hybrid pixel detectors are utilized for the rapid-scan time-resolved SAXS and WAXD measurements. The Raman unit consists of a compact probe with a near-infrared excitation laser operating at a wavelength of 1064 nm. This long-wavelength laser produces less fluorescence than conventional excitation lasers with wavelengths of 532 or 785 nm. The performance of this system was tested by investigating the thermally induced ferroelectric phase transition of vinylidene fluoride–trifluoroethylene (VDF-TrFE) copolymers. It has been demonstrated that the combination of SAXS, WAXD and Raman techniques gives useful information for revealing the relationship between the structural change in the crystal lattice and the morphological change in the lamellar stacking mode in polymer samples of complicated hierarchical structure.

scholarly journals The atomic scattering factor for X-rays in the region of anomalous dispersion

1933 ◽  
Vol 139 (838) ◽  
pp. 459-466 ◽  
Keyword(s):  
Free Electron ◽  
Scattered Radiation ◽  
Wave Length ◽  
Anomalous Dispersion ◽  
X Rays ◽  
Characteristic Frequencies ◽  
X Ray ◽  
Atomic Scattering Factor ◽  
Atomic Scattering ◽  
Scattering Factor

The atomic scattering factor ( f -factor) for X-rays is the ratio of the amplitude of the X-rays scattered by a given atom and that scattered according to the classical theory by one single free electron. It is given as a function of sin ϑ/λ, λ being the wave-length of the X-rays, 2ϑ the angle between the primary and the scattered radiation. It is assumed to be independent of the wave-length so long as sin ϑ/λ remains constant. Recently, however, it has been shown both theoretically and experimentally that the last assumption is no longer valid, when the scattered frequency is in the neighbourhood of one of the characteristic frequencies of the scattering element. The first to show the influence of the anomalous dispersion on the f factor were Mark and Szilard, who reflected strontium and bromine radiations by a rubidium bromide crystal. Theoretically the problem was dealt with by Coster, Knol and Prins in their investigation of the influence of the polarity of zincblende on the intensity of X-ray reflection and later on once more by Gloeker and Schäfer.

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