Question

How to derive the divergence leading to Kohn anomalies?

Answer 1

A diffraction grating, a laser pointer of known wavelength, an optical bench, a target ... A typical grating has density of 250 lines/mm. ... D = the distance from the grating to the screen .

Answer 2

A Kohn anomaly is an anomaly in the dispersion relation of a phonon branch in a ... of a metal a Kohn anomaly is a discontinuity in the derivative of the dispersion relation that occurs ...