What happens when we rotate crystal while shooting electrons at it?

In summary, the conversation discusses the diffraction of electrons when a narrow beam is shot at a crystal. The angle between the incoming beam and crystal planes is typically constant, but if the crystal is rotated, the angle changes and the positions of the maximums and minimums on the screen may also change. The speaker suggests using a standard youngs interference experiment to understand the effects of rotating the crystal. Additionally, the conversation mentions that the geometry of the crystal can also affect the diffraction patterns. The problem being discussed is a specific and complex one, and the speaker has posted it in a homework and coursework section for further discussion.
  • #1
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I know that if we shoot narrow beam of electrons at the crystal (we don't change the angle) we will get a diffraction of electrons according to the brag's law. Therefore we get minimums and maximums on the screen around the crystal.

Until now we have been dealing with problems where ##\vartheta## (this is an angle between an incoming beam and crystal planes) was constant. It meant that crystal wasn't rotating. To find maximums and minimums we have instead been rotating a sensor around the crystal.

But what would happen if we rotated the crystal? This would mean that we are changing the angle ##\vartheta##! Would minimums and maximums move around the screen or would they only appear and disappear? What is different than before?

A good picture is worth 1000 words.
 
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  • #2
You can probably work it out just by figuring the conditions for diffraction ... start with the standard youngs interference experiment and see what happens when you rotate the plane bearing the slits.

In electron diffraction experiments, the crystal is usually thin in one direction and thick in the other two - so you get extra effects from the geometry.
 
  • #3

1. What is the purpose of rotating a crystal while shooting electrons at it?

The purpose of rotating a crystal while shooting electrons at it is to gather information about the crystal's atomic structure. By rotating the crystal, we can obtain diffraction patterns from different angles, which allows us to analyze the arrangement of atoms within the crystal.

2. How does rotating the crystal affect the diffraction pattern?

Rotating the crystal can change the orientation of the crystal lattice, which in turn can affect the diffraction pattern. This is because the diffraction pattern is dependent on the arrangement of atoms within the crystal.

3. Can rotating the crystal improve the quality of the diffraction pattern?

Yes, rotating the crystal can improve the quality of the diffraction pattern. By obtaining diffraction patterns from multiple angles, we can obtain a more complete and accurate picture of the crystal's atomic structure.

4. Is there a specific speed or direction in which the crystal should be rotated?

The speed and direction of rotation can vary depending on the specific experiment and crystal being studied. In general, the rotation should be slow and consistent to avoid blurring the diffraction pattern.

5. Are there any limitations to rotating a crystal while shooting electrons at it?

There can be limitations to rotating a crystal while shooting electrons, such as the sensitivity of the equipment or the stability of the crystal. Additionally, rotating the crystal may not be necessary or beneficial for certain experiments or crystals.

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