These objects are dispersed away from a Fermi surface in Kohn Scattering. A third one of these particles is created when two of them collide in the Umklapp process, which is distinguished from their normal process by conservation of momentum. In florescence, their namesake sideband is shifted to a higher frequency during absorption. Usually divided into thermal, optical, and acoustic types, Debye 
These objects are dispersed away from a Fermi surface in Kohn Scattering. A third one of these particles is created when two of them collide in the Umklapp process, which is distinguished from their normal process by conservation of momentum. In florescence, their namesake sideband is shifted to a higher frequency during absorption. Usually divided into thermal, optical, and acoustic types, Debye integrated over all of their vibrational modes in order to derive his specific heat model. They obey the oscillatory conditions of their Brillouin zones, and they are usually used to explain thermal and electrical conductivity. FTP, name this quasi-particles, the quantized versions of lattice vibrations.
These objects are dispersed away from a Fermi surface in Kohn Scattering.
{Phonons}