Effect of Charge Density Waves on Reflectance Spectra of TaS₃and NbSe₃

Abstract

We report new reflectance results in the plasmon region of orthorhombicTaS 3 (single crystal) through the Peierls transition temperature and near the plasmon region of monoclinic NbSe 3 as a function of temperature. The optical spectra yield the dielectric constant due to core electrons, mass density and electron relaxation time. Furthermore, we discuss the modification of one electron excitations and plasmon collective excitations through charge density wave (CDW) transitions and assign these anomalies in TaS 3 to its normal-incommensurate (215±10 K) and incommensurate-commensurate (170±20 K) transitions in TaS 3 . In NbSe 3 , no modifications are observed through the normal-incommensurate CDW transition temperature (140 K).