Strong optical phonon mode of natural seraphinite probed by terahertz time-domain spectroscopy

Abstract

The natural seraphinite has the optical phonon modes in the frequency range from 0.1 to 2 THz. The observed absorption modes at 0.8, 1.2, and 0.96 THz are understood as infrared active phonon modes of Au(z) and Bu(x, y) symmetries, respectively. The 0.96 THz mode is, in particular, strong and narrow comparable to the reported 0.53 THz mode in α-lactose monohydrate. Experiments carried out by THz time-domain spectroscopy shows a good agreement with theoretical analysis based on the phonon-polarition dispersion relation.