Raman study of phonons and intraband electronic excitations in antimony

Line shapes of the zone-center optic modes $E_g$ and $A_{1g}$ in Sb have been measured at 80 K by Raman scattering. The results indicate asymmetry in the wings. The $E_g$ mode, in particular, shows a Fano line shape which is believed to arise from the interaction between the phonon and intraband electronic Raman scattering within the penetration depth of the metal. Though the cross section for the latter process is usually small for normal metals, in antimony because of the anisotropic multivalleyed Fermi surface and small effective mass of the carriers, it is likely to be significant.