Transport and optics in quasi-one-dimensional organic conductors

We review the transport and optical properties of an extended series of low dimensional organic Bechgaard conductors, which are hosting the first organic superconductor (TMTSF)(2)PF6. It is shown that all compounds of this family are one-dimensional Mott insulators with an activation energy for longitudinal transport depending on their chemical composition and decreasing under pressure. This activation energy in the transport results vanishes at a (chemical) pressure induced dimensionality crossover, while a gap feature is still observable in the far-infrared spectrum. Particularly, according to the data of transverse transport, the signature of a gap in the quasi particle spectrum is observable even when the longitudinal transport becomes metal-like. In this survey, we address a variety of relevant problems and concepts associated with the physics of an interacting electron gas in low dimensions, such as non-Fermi liquid behavior, dimensionality crossover, and specifically the appearance of the Luttinger liquid state.