phonons!

[nibot]

The energy of a lattice vibration is quantized. The quantum energy is called a phonon in analogy with the photon of the electromagnetic wave. Elastic waves in crystals are made up of phonons. Thermal vibrations in crystals are thermally excited phonons, like the thermally excited photons of black-body electromagnetic radiation in a cavity. The energy of an elastic mode of angular frequency ω is ε=(n+1/2)ℏω when the mode is occupied by n phonons.

Solid state physics is a lot more interesting than I'd thought! (Then they go on to talk about plasmons, magnons, polarons, and excitons...) Even planck's constant shows up!

Comments

[ragnus.livejournal.com]

heh

which physics class is this?

[nibot.livejournal.com]

Well, I'm reading the Kittel's Introduction to Solid State Physics book (see nibot_lab for a full reference). If you wanted it as part of a course, it would be Physics 141A/B.

[transplantgn.livejournal.com]

as much as I wanna know what that mean and I actually do I went crosseeyed reading that abotu 4 times.

[nibot.livejournal.com]

I think your user icon is making me crosseyed.

[transplantgn.livejournal.com]

sorry. I really do wanna know what your talking about.

emma is curious because emma is a physics groupie...

[emidala.livejournal.com]

tobin, what kind of physics have you been doing before?

Re: emma is curious because emma is a physics groupie...

[nibot.livejournal.com]

I've taken courses in quantum mechanics (137A and 137B in Berkeley) and in particle physics (fysik 225, lunds universitet), and worked at cern for the summer. I'm currently figuring out how I can take all the rest of the physics courses I need before I can apply to a physics PhD program. (-: At the moment I'm working at LBL in an electron microscope lab, hence the reading in solid state physics.

Re: emma is curious because emma is a physics groupie...

[emidala.livejournal.com]

come to princeton! I know half the physics department, they're super nice, super smart and they'll love you so they'll get you in. :)

Re: emma is curious because emma is a physics groupie...

[nibot.livejournal.com]

oh, I'd love to... but I think my chances of being admitted at the moment are solidly zero. )-:

Re: emma is curious because emma is a physics groupie...

[nibot.livejournal.com]

have you seen the official string theory site (http://superstringtheory.com/)? it's nifty.

[shamster.livejournal.com]

Shouldn't the angular quantum number (nu) be used instead of n? Or do you not care for nomenclatural preservation?

Also, what's the advantage in defining vibrations as phonons instead of just saying 'vibrations'. And... What's meant by a "thermal" vibration?

What's the special part about planck's const.?

[nibot.livejournal.com]

I've always seen quantum states indexed by n.

Phonons are more than vibrations precisely because they are quantized in energy in a way analagous to elementary particles and also because they act like particles, which is pretty outrageous at first glance. But I just started reading about them today, so I am not so sure about all the possible wonders of phonons.

Thermal vibrations... I assume that means that it's the inherent vibration described by temperature. (As opposed by outside impulse?)

Planck's constant is solidly a quantum mechanical thing, and to see it showing up in the vibrational modes of macroscopic solids is shocking. Well, kind of.

Well, I don't know much about it yet, but it seems like a very interesting way of describing things. Apparently quite useful too, since you can - apparently - start talking about "electron/phonon interactions" as if a phonon were a real particle.

[nibot.livejournal.com]

Also: Phonons of wavevector k will interact with particles such as photons, neutrons, and electrons as if it had a momentum hk/2π. In inelastic scattering, the phonon really behaves like a particle. I think this is because the atoms in the crystal act like simple harmonic oscillators, which in turn have quantized vibrational modes... but there's more to it.

[shamster.livejournal.com]

planck's constant shows up everywhere. I've seen it used in solid state before.

I suppose you're right about the n, it's the energy quantum number... the nu, which I meant to say 'l' is the angular momentum quantum number for elementary particles (read:electrons)

disgruntled south african

[pixieza.livejournal.com]

nah,

solid state physics is BORING!
argument:
1. half the department in cape town does solid state physics
2. they are all weird and boring
-> solid state physics is boring.

I find those phonon things really weird - they almost seem like the vibrational energy people felt left out without having exciting new particles so they invented them.

[tjernobyl.livejournal.com]

Also, phonon!