Reflection spectroscopic study of organic conductors

The author reviews the low-energy optical transitions in quasi one- and two-dimensional organic conductors studied by polarized reflection spectroscopy. The characteristic optical properties of organic conductors are the strong anisotropy, electron-electron interaction, and coupling with intra-molecular vibration. The method to extract the transfer integrals in anisotropic tight-binding bands is described for several organic conductors. The correlation effect has a big influence on the line shape of the optical conductivity spectrum in the intra-band transition region. The electron-molecular vibration coupling provides us with rich information on the structural fluctuations and structural changes during the phase transition. The observation of plasmons resulting from the mixing with the transverse excitation is caused by the strong anisotropy in electronic structure.