Optical properties of (TTF) (TCNQ) in the visible and infrared

Polarized optical studies of single crystals and polycrystalline compactions of the organic salt (TTF) (TCNQ) are reported. Metallic behavior is observed for light polarized parallel to the conducting axis. The plasma edge occurs at 1.4 μm with metallic reflection observed in the i.r. The plasma frequency $\text{(}\text{h}\text{?}\text{ω}{}_{\mathrm{p}}\text{=}\text{1.2eV}\text{)}$ leads to an optical effective mass $\text{m}{}^1\text{=}\text{5}\text{m}{}_{\mathrm{e}}$ implying a tight-binding transfer integral of 0.1 eV in agreement with estimates obtained from other measurements. The scattering time, τ, as determined from the shape of the reflectance curve, yields a room temperature metallic conductivity of 10³(Ω-cm)^-1 in good agreement with the measured d.c. value. An estimate of the dimensionless electron-phonon coupling constant is obtained from the measured value of τ,λ_ph?1.3. The strong anisotropic absorption in the visible portion of the spectrum is attributed to interband transitions.