- #1
exciton
- 14
- 0
Hi guys,
I don't understand how one would exactly determine a dispersion relation
of phonons experimentally.
There are two equations, one for momentum and one for energy conservation:
[tex]\vec{k} - \vec{k^{'}} = \vec{G} + \vec{K} [/tex]
[tex]\omega - \omega ^{'} = \omega(K) [/tex]
where [tex]\omega(K)[/tex] is the energy difference of the scattered neutrons,
[tex]\vec{k} [/tex], [tex] \vec{k^{'}} [/tex] are the wave vectors of the neutrons before and
after scattering, [tex]\vec{K} [/tex] is the created phonon and [tex]\vec{G} [/tex] a
reciprocal lattice vector.
The question is, how is the difference [tex]\vec{k} - \vec{k^{'}} [/tex] respectively [tex]\vec{K} [/tex] determined experimentally?
Of course I also have to know [tex]\vec{G} [/tex].
thanks
I don't understand how one would exactly determine a dispersion relation
of phonons experimentally.
There are two equations, one for momentum and one for energy conservation:
[tex]\vec{k} - \vec{k^{'}} = \vec{G} + \vec{K} [/tex]
[tex]\omega - \omega ^{'} = \omega(K) [/tex]
where [tex]\omega(K)[/tex] is the energy difference of the scattered neutrons,
[tex]\vec{k} [/tex], [tex] \vec{k^{'}} [/tex] are the wave vectors of the neutrons before and
after scattering, [tex]\vec{K} [/tex] is the created phonon and [tex]\vec{G} [/tex] a
reciprocal lattice vector.
The question is, how is the difference [tex]\vec{k} - \vec{k^{'}} [/tex] respectively [tex]\vec{K} [/tex] determined experimentally?
Of course I also have to know [tex]\vec{G} [/tex].
thanks