X-ray diffraction; atomic form factor

Click For Summary
SUMMARY

The discussion centers on the atomic form factor of an fcc lattice of Buckyballs (C60 atoms) and its impact on X-ray diffraction peaks. It is established that the atomic form factor can be expressed as f~(sin(Gr))/G, multiplied by constants. The weaker intensity of the (2,0,0) X-ray diffraction peak compared to the (1,1,1) peak is attributed to the inverse relationship between d-spacing and theta, as described by Bragg's Law. As the Miller index increases, the d-spacing decreases, leading to higher theta values where the form factor diminishes.

PREREQUISITES
  • Understanding of atomic form factors in crystallography
  • Familiarity with X-ray diffraction techniques
  • Knowledge of Bragg's Law and Miller indices
  • Basic grasp of mathematical expressions involving sine and constants
NEXT STEPS
  • Study the derivation of the atomic form factor for different crystal structures
  • Learn about the calculation of X-ray diffraction intensities using Bragg's Law
  • Explore the relationship between Miller indices and d-spacing in detail
  • Investigate the effects of varying theta on the atomic form factor
USEFUL FOR

Researchers in materials science, physicists studying crystallography, and anyone involved in X-ray diffraction analysis of complex structures like Buckyballs.

physics_fun
Messages
28
Reaction score
0
Hey,

I'm working on a problem about the atomic form factor. I found that the atomic form factor of an fcc lattice of Buckyballs (C60 atoms) looks like f~(sin(Gr))/G multiplied bij some constants.

The question is now to explain from this atomic form factor why the (2,0,0) X-ray diffraction peak is much weaker (compared, for example, to the (1,1,1) peak).

I tried to put the numbers in, but every time I try this, I get (almost) the same answers for the two peaks...:(

What am I doing wrong?

edit: r=constant
 
Physics news on Phys.org
that is because, 002 is at an higher 2theta value, if you look at braggs law you can see that the d spacing is invers related to theta. Bigger miller index, means smalle d-spacing which in turns meens a larger theta value. And as the form factor falls of with bigger theta values, that is the explanation..
 
Hey!
Can u explain how did you calculate the form factor?
I don't know how to pass from the vectoric experession to an expression I'll be able to calculate..
tnx a lot!
 

Similar threads

Undergrad What happens to X-rays if they do not meet Bragg's law?
  • · Replies 1 ·
Replies
1
Views
2K
X-Ray Diffraction Homework: Deriving (2theta) Values
  • · Replies 1 ·
Replies
1
Views
4K
Atomic Form Factor Homework: NaCl, LiF, GaP, Si
  • · Replies 3 ·
Replies
3
Views
3K
Undergrad Understanding Ewald's sphere in the context of X-Ray diffraction
  • · Replies 3 ·
Replies
3
Views
6K
Which lattice plane shows no diffraction peak in fcc crystal?
  • · Replies 1 ·
Replies
1
Views
3K
How Do Bragg Peak Intensity Ratios Differ in Ca and CaF2 X-Ray Diffraction?
  • · Replies 1 ·
Replies
1
Views
2K
Undergrad Van Laue Formulation: X-ray Diffraction from Crystal Structure
  • · Replies 1 ·
Replies
1
Views
2K
Undergrad Why the reflected angle is the same as incident in x-ray diffraction?
  • · Replies 4 ·
Replies
4
Views
5K
Undergrad Characteristic X Rays: Understanding Atom Reversion
  • · Replies 1 ·
Replies
1
Views
2K
Need help using the atomic form factor
  • · Replies 1 ·
Replies
1
Views
1K