umklapp process

by aaaa202
Tags: process, umklapp
aaaa202 is offline
Oct30-13, 03:52 PM
P: 995
This occur when two phonons interact and the sum of their momenta add to a new wavevector outside the new Brillioun zone. The resulting wavevector is then mapped back into the Brillioun zone by subtraction of a suitable reciprocal lattice vector.
I don't think I understand the physics in all of this. I understand the idea but what is physically going on in this process and where does the leftover momentum go?
Phys.Org News Partner Physics news on
Chameleon crystals could enable active camouflage (w/ video)
Atomic switcheroo explains origins of thin-film solar cell mystery
X-ray laser experiment explores how specially shocked material gets stronger
UltrafastPED is offline
Oct30-13, 04:11 PM
P: 1,346
The left over energy absorbed by the crystal; the momentum is not "real momentum" - it is crystal momentum, which is not conserved.

DrDu is offline
Oct31-13, 01:59 AM
Sci Advisor
P: 3,375
Well, of course also real momentum is conserved. It is taken up completely by the lattice.

Register to reply

Related Discussions
Umklapp Scattering & Conservation of Energy Atomic, Solid State, Comp. Physics 2
Random process derived from Markov process Set Theory, Logic, Probability, Statistics 4
thermal phonon conductivity and umklapp process Atomic, Solid State, Comp. Physics 11
umklapp scattering Atomic, Solid State, Comp. Physics 1
umklapp processes Advanced Physics Homework 4