# Search results

• Users: Repetit
• In Atomic and Condensed Matter
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1. ### Relation between conductivity and permittivity

Hey. Is the conductivity of a material related to the dielectric constant (permittivity) in some way? And what about the electrical susceptibility? Thanks
2. ### Law of Mass Action

Thank you for the answers! It makes more sense to me now.
3. ### Law of Mass Action

In a semiconductor the law of mass action states that the product of the electron concentration and the hole concentration is always equal to the square of the intrinsic carrier concentration (at a given temperature), i.e.: n p = n_i^2 My book states that this law is valid for...
4. ### Dielectric function

Are we talking probing with light here? In that case the frequency and the wavevector are not independent but related by \omega/k=c, right?
5. ### Exploring the Microscopic World: Visualizing Atomic Physics

Like Neu said, the world of atoms and molecules is governed by quantum mechanics, and quantum mechanics is so much different from macroscopic quantities like basketballs. It is impossible to draw an analogy between the two. In school atoms are sometimes visualized as planets (the nucleus)...
6. ### Understanding Effective Mass in Solid State Physics

But what causes an electron in a crystal to have a larger acceleration under an applied force F than a free electron in vacuum under the same applied force? Why doesn't the effect from all the other electrons in a crystal just cancel out because the effect is the same in all directions?
7. ### Why only first brillouin zone?

The reason why it is only necessary to consider the first Brillouin zone lies in the fact that the wave function in a crystal is written as a function with the periodicity of the lattice times a plane wave, so that in one dimension: \psi_{nk}(x) = e^{i k r} u_{nk}(x) The plane wave is...
8. ### What is the fermi energy measured relative to?

Hey! When we say that the fermi energy of a certain metal is for example 2 eV what are the 2 eV measure relative to? The top of the valence band? If so, wouldn't the fermi energy of a semiconductor at 0 K be 0 eV? Thanks
9. ### Plasmons, Surface Plasmons, Localized Plasmons Im confused!

I don't really know where this thread belongs so I'll just put it here. Im pretty confused about all these terms. I mean, a plasmon is a collective oscillation of the electrons in the material (right?), and a surface plasmon is a plasmon traveling along the surface of a material, but what are...
10. ### Strength of a covalent bond

Thanks for the reply! Your are right, the temperature is closer to 20,000K, I made a dumb mistake when calculating the value. I believe things are not as simple as I wanted them to be, because time and other factors play an important role as well.
11. ### Best Solid State Physics Book

Hey! You might want to try out Ashcroft and Mermins book entitled (surprise surprise...) "Solid State Physics"! The deriviations are more detailed than in Kittels book and therefore easier to follow. In addition, the physical explanations are in my opinion better and more detailed. One...
12. ### Strength of a covalent bond

Hey! I want to estimate the temperature needed to break a covalent bond of strength 1.70 eV. Whould it be correct to compare the thermal energy k_B T to the bond strength and find the temperature needed to make the thermal energy larger than the bond strength? I get a temperature of about...
13. ### Binding energy and work function of a solid?

Thanks for the help! Good to know that I was not too wrong on the meaning of these terms :-)
14. ### Binding energy and work function of a solid?

Can someone explain the difference to me? Is it correct that the binding energy is the energy needed to bring an electron to the fermi level, and the work function it the energy needed to bring an electron from the fermi level to the vacuum level? What are typical values of the binding energy...
15. ### Exciton binding energy

Hey! Can someone help me calculate the binding energy of an exciton? I have been told to use the Rydberg energy but isn't the Rydberg energy derived using the kinetic energy of an atom in a circular orbit about a positve core (hydrogen atom), and the coulomb potential between the two? In an...