X-ray and electron microscope diffraction patterns

In summary, the interpretation of dark and bright spots in x-ray and electron diffraction patterns depends on the detection technique and the spots represent positions in reciprocal space rather than the actual positions of atoms. In the case of electron diffraction patterns, the bright spots correspond to reflections formed by the planes of atoms, with the distance between spots being in reciprocal space.
  • #1
jbar18
53
0
Hey,

I'm having trouble finding a clear answer anywhere. When you have a x-ray diffraction pattern, do the dark spots correspond to the positions of atoms? Or do they represent the position of atoms in reciprocal space or something like that? It would seem natural to assume that the peaks are the atoms themselves but I keep seeing reciprocal space and Fourier transforms coming up wherever I look and so I don't want to assume anything.

One other thing, is this the same for the bright spots in an electron diffraction pattern?

Thanks
 
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  • #2
Whether the spots are dark or bright depends on the detection technique. I suppose you are referring to spots on photographic film in the case of X-rays and spots on a fluorescent screen in the case of electron diffraction?
In both cases the spots don't belong to the real atoms but to positions in reciprocal space.
That means there is a spot whenever planes formed by the atoms have such an orientation with respect to the incident radiation that the Bragg condition for reflection is fulfilled.
 
  • #3
jbar18 said:
Hey,

I'm having trouble finding a clear answer anywhere. When you have a x-ray diffraction pattern, do the dark spots correspond to the positions of atoms? Or do they represent the position of atoms in reciprocal space or something like that? It would seem natural to assume that the peaks are the atoms themselves but I keep seeing reciprocal space and Fourier transforms coming up wherever I look and so I don't want to assume anything.

One other thing, is this the same for the bright spots in an electron diffraction pattern?

Thanks

Hi,

For electron microscope diffraction patterns (DP), the each bright spot corresponds to the reflection formed by the plan formed by atoms. And the distance between spots are in inverse, i.e. as DrDU said they are recriprocal distance. [some reflections are forbidden in electron microscope DPs!].
 

1. What is the difference between X-ray and electron microscope diffraction patterns?

X-ray diffraction patterns are created by passing a beam of X-rays through a crystalline sample, while electron microscope diffraction patterns are created by passing a beam of electrons through a thin sample. X-ray diffraction is used to study the atomic structure of materials, while electron microscope diffraction is used to study the nanoscale structure of materials.

2. How are diffraction patterns used in scientific research?

Diffraction patterns are used to determine the atomic or nanoscale structure of materials. By analyzing the diffraction pattern, scientists can identify the arrangement of atoms or molecules within a sample, which can provide valuable information about the properties and behavior of the material.

3. What factors affect the appearance of a diffraction pattern?

The appearance of a diffraction pattern can be affected by the type of radiation or particles used, the wavelength or energy of the radiation, the orientation of the sample, and the size and shape of the crystals within the sample.

4. Can diffraction patterns be used to identify unknown substances?

Yes, diffraction patterns can be used to identify unknown substances by comparing the pattern to known reference patterns. Each substance has a unique diffraction pattern that can be used for identification.

5. How has technology advanced the study of diffraction patterns?

Technology has allowed for the development of more powerful X-ray and electron microscopes, which can produce higher resolution diffraction patterns. Additionally, the use of computational methods and software has made it easier to analyze and interpret diffraction patterns, allowing for more accurate and efficient research.

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