2. Computer Practicum
You can
download the files from the Practicum here.
Please use 'tar xfz' to
uncompress on a UNIX system.
Term Paper (due @ session
6):
Since we did not discuss indexing of X-ray crystal diffraction patterns
in great detail in class you will write a minimum 5 page term paper
based on chapter 5 in McPherson's
book. Handwritten notes OK. Here is your assignment:
(i) Read the chapter.
(ii) What is the typical wavelength of X-rays? Given the wavelength of
electrons, 0.02 Angstrom at 300kV, compare the sizes of both the X-ray
and electron diffraction Ewald spheres relative to a typical crystal
lattice in
reciprocal space. Assume a diffraction peak at (1/Angstrom), what is
the angle of both scattered electrons and X-rays relative to the
incident beam axis? What does this tell you about the geometry of an
electron microscope vs. that of an x-ray detector?
(iii) Discuss how one
can detect screw axes in diffraction patterns if the translations
(=phases) are lost.
(iv)
Discuss in detail how 1.-5. on p. 133 (PDF page 8, right side) are done
(in your own words, after reading the text following p. 133).