Terahertz Spectroscopy in Advanced Materials Science

Materials science is the interdisciplinary field to study material properties and their functionality on the basis of physics, chemistry, metallurgy, and mineralogy. Vibrational spectroscopy such as infrared spectroscopy and Raman spectroscopy is a powerful tool to investigate characteristic atomic vibrations. Especially, in the terahertz frequency range, vibrational modes are related to collective atomic vibrations reflecting interatomic/molecular interactions, characteristic units, and medium range order. Recent progress of terahertz vibrational spectroscopy using terahertz-time-domain spectroscopy, terahertz time-domain spectroscopic ellipsometry, and far-infrared spectroscopy is reviewed in advanced materials science on glassy and crystalline pharmaceuticals, ferroelectrics, and polar metallic materials. Using the terahertz spectra, phonons, polaritons, and conduction electrons of these materials are discussed.