Matter/Electron Waves and the Davisson-Germer Experiment

• Yosty22
In summary, the Davisson-Germer Experiment involves scattering a beam of low-speed electrons from a polycrystalline nickel target. The experiment showed that the electron is also a matter-wave and the diffraction peaks occur when the incident beam hits the crystal surface perpendicularly. However, it is possible for the peaks to arise at different angles, as mentioned in Bragg's law. The glancing angle is the complement of the angle of incidence between a ray and a plane surface.
Yosty22

Homework Statement

This is a conceptual question that I am not quite sure about. In the Davisson-Germer Experiment (details here), do the electron diffraction peaks that occur only show up if the incident beam of electrons hits the crystal surface perpendicularly?

The Attempt at a Solution

I was really confused when reading this in my textbook when it relates to this question. The book talks a lot about Davisson and Germer's initial intent which was to "attempt to understand the arrangement of atoms on the surface of a nickel sample by elastically scattering a beam of low-speed electrons from a polycrystalline nickel target. (If you are unfamiliar with the story, someone dropped a flask of liquid air on the vacuum system, oxidizing the nickel target. They then realized that the crystalline structures it created scattering of electrons, showing that the electron is also a matter-wave).

However, in my textbook, they talk about \alpha being the target orientation, and that is 90°. After that brief mention, they do not really speak of it again. Because of this, I am a little unsure as what to believe. Would these peaks arise if the angle was different than 90°?

Wikipedia has this 90° in its story too. But they refer to Bragg's law for the angles. There the pictures have angle of incidence = exit angle. I think perpendicular incidence isn't essential, but it gives a nice expression for angles of constructive interference.

That is what I thought as well. I thought that the 90 degree angle makes it "easier" - like the simplest case of what actually happens. However, I did not know if there was an actual reason why it does or does not matter.

Thank you.

What is glancing angle?
I found this definition but I am not getting this.
the angle between a ray incident on a plane surface and the surface,as of a beam of electrons incident on a crystal;the complement of the angle of incidence.

What is matter and how is it related to electron waves?

Matter is anything that has mass and takes up space. In the quantum world, matter can also exhibit wave-like behavior, including electrons. The concept of matter and electron waves is based on the theory of quantum mechanics, which describes the behavior of particles at the atomic or subatomic level.

What is the Davisson-Germer Experiment and why is it important?

The Davisson-Germer Experiment was a landmark experiment conducted in 1927 by Clinton Davisson and Lester Germer. They observed the diffraction of electrons off a crystal of nickel, confirming the wave-like nature of electrons. This experiment provided strong evidence for the wave-particle duality of matter, which is a fundamental concept in quantum mechanics.

How does the Davisson-Germer Experiment support the concept of electron waves?

The Davisson-Germer Experiment demonstrated that electrons, which are considered to be particles, can also exhibit wave-like behavior. This was observed through the diffraction pattern produced by the electrons as they passed through the crystal of nickel. This supported the idea that electrons have both particle and wave properties, which is a fundamental concept in quantum mechanics.

What are some practical applications of the Davisson-Germer Experiment?

The Davisson-Germer Experiment contributed to the development of electron microscopy, which is a powerful tool used in various fields such as biology, materials science, and nanotechnology. It also played a crucial role in the development of quantum mechanics, which has led to many technological advancements, including transistors, lasers, and computer memory.

Are there any limitations to the Davisson-Germer Experiment?

One limitation of the Davisson-Germer Experiment is that it only applies to particles with low mass, such as electrons. It cannot be used to study the wave-like behavior of larger particles, such as atoms or molecules. Additionally, the experiment is limited to studying the diffraction of electrons off a crystalline surface and cannot be used to study other types of diffraction phenomena.

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