Absolutely right Volker!
XRD - In the diffraction space (reciprocal space) by measuring deviation from ideal Bragg condition in fractions of an Arc Sec for a single crystal it is possible to resolve strain fields in the FEMTOMETER scale. X-ray Rocking Curve Analysis!
See example of ZnSe (224) study:
Figure B: Complete Data Set - http://www.flickr.com/photos/85210325@N04/8294404556/sizes/h/in/set-72157632729045818/
Image portrays several important elements of the analyses in one collage. It includes:
a. Relative Bragg Peak Position Map: The map of the absolute value of Omega for the most intense peak on the RCP for each pixel. We have used histogram expansion to create better visual contrast in pseudo color to the human eye.
b. Relative Bragg FWHM Map: The map of the FWHM for the most intense Bragg peak on the RCP for each pixel. Histogram expansion used to enhance perceived image contrast in pseudo color.
c. The existence of the additional un-indexed reflection towards the top right corner of the subject (224) reflection. By monitoring the nano-structure in multiple (hkl) planes it would be possible to reconstruct the 3D strain field in the crystal lattice. Notably the strain fields in the two visible reflections are not identical.
d. Actual sample image with estimate of size.
e. Omega-X & Omega-Y images are a display of up to 200 RCP’s along each cursor line. The RCP’s are displayed using pseudo color scale to depict pixel intensity as a function of Omega. The cursor “cross hair” RCP is highlighted.
f. Application of image contour correction using actual sample dimensions to compensate for image distortions due to XRD optics and system. Final true sampling VOXEL size estimate – 34umHx130umVx1.1umD. In the case of conventional diffractometer with a 0D detector, it usually involves a 2-3mm sampling size unless limited by slits.
g. Ability to monitor and record intricate details of the crystallographic sub-structure for the depth of examination based on the (hkl). Ability to follow sub-grains in depth topographically.
h. Images of the type of detector, diffractometer, optics and geometry employed to create the initial data. All rocking curve analyses and corresponding reciprocal space images have been generated using Onsight Technology’s DARC software package. The original image is a FOUR dimensional image in video – X, Y, Omega, & Intensity.
- Badges
- Science method
- Similar topics
- Methodology
- Crystallography