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Materials Science 142
Applications of Diffraction Techniques

Homework Assignment 2: Plane Group Symmetry

Assigned: 1/18/12
Due:1/25/12, 5pm

Goal: Determine the symmetries present in a 2-dimensional pattern; identify an appropriate unit cell. Seven patterns are to be analyzed.

  1. Identify rotation axes. Note these on your pattern using the appropriate symbol.
  2. Identify mirror planes. Draw these as solid blue lines.
  3. Identify glide planes. Draw these as dotted red lines.
  4. Outline the unit cell in black. Indicate the number of lattice points per unit cell.


Make sure your patterns are relatively neat and legible. If you were not in lab, or would like to get additional copies of the 2-d patterns, you can download them here.

2-D Patterns

pattern 1
pattern 2
pattern 3
pattern 4
pattern 5
pattern 6
pattern 7

Preparation for X-ray Data Analysis:

X-ray data analysis will be performed in this class using XPert HighScore and XPert Plus Software from Panalytical. You are permitted to install these packages on your personal computer on the condition that you uninstall them at the end of the term. If you cannot abide by this condition, or you simply do not to do the installation, you can use the computers in Steele 337 (the diffractometer lab), which already have this software. In this assignment you will use the HighScore program in particular.  It is advised, however, that if you are doing an installation, you do both packages at the same time.

All required files can be accessed from the links below.

Referring to the detailed instructions provided, import the example data file (*.xrdml file). Perform a background subtraction and strip kalpha-2 peaks using the default parameters. Export the image of the diffraction pattern as a bitmap and insert it into a document (i.e. word) file. Also export the data as ascii and plot in Origin. Convince yourself that the data conversion was carried out properly by comparing to the two plots. Provide meaningful figure captions.


Software instructions
Example data file (download the compressed *.rar file, then decompress it locally).


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