This is what your event will look like after going live. It may take up to 60 seconds for your changes to apply.
Interested
Add to CalendarAdd to Cal
B-13: Mathematics of Two-Dimensional X-Ray Diffraction

Bob He

Bruker AXS

ABSTRACT

The 2D diffraction pattern contains the scattering intensity distribution as a function of two orthogonal angles. One is the Bragg angle 2q and the other is the azimuthal angle about the incident x-ray beam, denoted by g. A 2D diffraction pattern can be analyzed directly or by data reduction to the intensity distribution along g or 2q. The data integration can reduce the 2D pattern into a diffraction profile analogs to the conventional diffraction pattern so that many existing algorithms and software can be used for the data evaluation. However, the materials structure information associated to the intensity distribution along g direction is lost through g-integration. The intensity distribution and 2q variation along g are associated to the orientation distribution, stress, crystallite size and size distribution.  

Single crystal and random powder represent two extreme cases of the diffraction samples. The Laue equations are suitable to interpret the diffraction pattern from single crystal. The Bragg law is more conveniently used for the diffraction pattern from a random powder. For most other samples and applications, the diffraction vector approach has been proved to be the genuine theory to interpret and evaluate the 2D diffraction data. The unit diffraction vector representing any feature in a 2D pattern measured in the laboratory coordinates can be transformed to the sample coordinates. A flow chart from the introduction of diffraction vector as a function of 2q and g, transformation of unit diffraction vector from laboratory coordinates into sample coordinates, and fundamental equations for stress, texture, and reciprocal mapping are displayed in the poster. 

Reference:

  1. Bob He, Two-dimensional X-ray Diffraction, 2nd Edition, John Wiley & Sons, (2018).
  2. Bob He, Two-dimensional Powder Diffraction, chapter 2.5 of International Tables for Crystallography, Volume H, Powder Diffraction, edited by C. J. Gilmore, J. A. Kaduk and H. Schenk, Wiley/International Union of Crystallography (IUCr), September 24, 2019.


Poster Session Link:

https://gather.town/invite?token=0pEoq7VP



If you have any questions for the presenter, please contact them by either one of the following ways:

Bob He Community Page Link

Email: bob.he@bruker.com