Terahertz Measurement of the Quasiparticle Mass Renormalization in Lead and Chromium

We study the optical conductivity of lead and chromium as a function of frequency and temperature using terahertz time-domain spectroscopy (THz-TDS). The optical conductivity is interpreted in terms of the extended Drude model (EDM), where the optical scattering rate and renormalized mass of the camers take on frequency as well as temperature dependence. Within the EDM framework, the theory of electron-phonon scattering yields expressions for the optical scattering rate and mass enhancement, dependent upon the transport-weighted Eliashberg spectral function. This thesis presents THz-TDS measurements of thin films of Pb and Cr. We compare results for the optical scattering rate and quasiparticle mass renormalization to theory and find a strong agreement.