I am doing Q2 from the 2007 paper and the last part is "which sections of the dispersion relation (for a diatomic linear chain) might it be possible to measure by studying the interactions of the crystal vibrations with light?"
I assume this is the optical band given the name.... but why? Nothing about the scattering approach means that you only get scattering if there is at least two atoms per primitive unit cell? Simple cubic lattices still scatter and they only have an acoustic band?
Thanks a lot!