X-ray Diffraction: Why Are Peaks of Different Intensities?

In summary, the intensity of peaks in an x-ray diffraction graph is determined by the angular dependence in the atomic form factor, with larger Miller indices corresponding to a decrease in intensity. This is why the peak for (110) in bcc is the largest and can be further explained in resources such as Wikipedia and books. Additionally, if the sample is composed of multiple elements, the varying form factors of each element can also contribute to different intensities in the diffraction pattern.
  • #1
abcdmichelle
18
0
This is not really a homework question but a more general plea for an explenation from someone! :)

In x-ray diffraction, you get a graph with different peaks that are particular to the composition of your sample. But, why are some peaks are of higher intesities then others? What is it about the sample/crystal structure that makes some peaks greater then other at certain angles?

thank you!
 
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  • #2
The intensity falls off with an increasing angle of diffraction (corresponding to larger Miller indices) due to the angular dependence in the atomic form factor. That is why the peak for (110) in bcc is the largest. It is briefly discussed on Wikipedia on the "Structure factor" page, but you can also find it discussed in books.

Also, if the mineral is not monotonic (more than one element), then different elements can have different form factors leading to varying intensities.
 

FAQ: X-ray Diffraction: Why Are Peaks of Different Intensities?

1. What is X-ray diffraction?

X-ray diffraction is a technique used to analyze the structure of materials by exposing them to X-rays and measuring the scattered radiation. It is commonly used in the fields of physics, chemistry, and materials science.

2. Why are peaks of different intensities observed in X-ray diffraction patterns?

The peaks in an X-ray diffraction pattern represent the diffraction of X-rays by the atoms in a material. The intensity of each peak is determined by the number of atoms in the material, as well as their arrangement and orientation in the crystal lattice. Therefore, peaks of different intensities indicate differences in the atomic structure of the material.

3. How is X-ray diffraction used to determine the crystal structure of a material?

X-ray diffraction patterns can be analyzed to determine the crystal structure of a material by comparing the positions and intensities of the peaks to known patterns of different crystal structures. This technique, known as X-ray crystallography, can provide valuable information about the arrangement of atoms in a material and its physical properties.

4. Can X-ray diffraction be used to identify different types of materials?

Yes, X-ray diffraction can be used to identify different types of materials by comparing their diffraction patterns to known patterns in a database. This is often used in materials analysis and quality control to identify and verify the composition of a material.

5. What are the limitations of X-ray diffraction in materials analysis?

While X-ray diffraction is a powerful tool for determining the crystal structure and composition of a material, it does have some limitations. For example, it cannot provide information about the atomic or molecular structure of non-crystalline materials, and it is sensitive to the sample preparation and orientation. Additionally, some materials may have very complex diffraction patterns, making analysis more challenging.

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