Discuss the importance and key role of Bragg’s law in X-ray
diffraction experiments.
Describe the developments in experimental approaches, advances
in instrumentation and techniques in X-ray diffraction experiments
from the era of von
Laue to the present day.
The relative intensity of Bragg reflections in X-ray powder
diffraction experiments is affected by several factors. Discuss
these factors and how these issues arise with an explanation of how
they are corrected (with the use of suitable diagrams where
appropriate).
Compare and...
Briefly describe the diffraction of x rays( or electrons) from
crystal planes. Derive Bragg law based on constructive and
extinctif interference. Indicate the difference in diffraction
between XRD and TEM.
How
are the interactions between X-Ray Diffraction with bilogical
molecules such as proteins and DNA?
What patterns could you observe in a XRD?
How do you do XRD of DNA?
Could you identify mutations by doing an XRD of DNA?
Explain:
a) The similarity between the electron and the X-ray diffraction
patterns of aluminium.
b) The line in the hydrogen atom spectrum splits into two when
placed in a magnetic field.
c) The appearance of coloured lines for H atom in the Balmer series
while the Lyman series can only be observed with an ultraviolet
lamp.
The first four peaks in the X-ray powder diffraction pattern of
sodalite are at 2 values of 9.97°, 14.12°, 17.32° and 20.02°. The
radiation used for the experiment was Cu K with = 1.5418 Å.
Determine the lattice type and calculate the length, a, of the
cubic unit-cell.
Assume that an X-ray diffraction pattern is taken from two
specimens of pure Ni. The two specimens are identical except that
one contains numerous twins, while the other is untwinned. Would
the XRD patterns show a larger number of diffraction peaks for the
specimen containing the twins? Explain the reasoning behind your
answer.
Describe the powder X-ray diffraction experiment. List the basic
components in your diagram and discuss the features/roles of each
component. Include Bragg’s Law as well as coherent and incoherent
scattering. What types of information can be obtained using this
technique? Pros and cons with respect to single crystal XRD?