Temperature Dependence of the Near-Infrared Optical Properties of Tetrathiofulvalinium Tetracyanoquinodimethane (TTF-TCNQ)

We report the near-normal-incidence reflectivity spectrum of single-crystal TTF-TCNQ in the range 0.2-2.0 μm. A Drude-like edge, persisting through the metal-insulator transition at 60°K, is observed near 1.3 μm for light polarized parallel to the conducting axis. The temperature dependence of the optical parameters ε0, τ, and ωp are discussed in conjunction with Hopfield's relation for the electron-phonon coupling constant. © 1973 The American Physical Society.