Surface characterization and surface electronic structure of organic quasi-one-dimensional charge transfer salts

We have thoroughly characterized the surfaces of the organic charge-transfer salts TTF-TCNQ and $(\mathrm{TMTSF}{)}_{2}{\mathrm{PF}}_{6}$ which are generally acknowledged as prototypical examples of one-dimensional conductors. In particular x-ray-induced photoemission spectroscopy turns out to be a valuable nondestructive diagnostic tool. We show that the observation of generic one-dimensional signatures in photoemission spectra of the valence band close to the Fermi level can be strongly affected by surface effects. Especially, great care must be exercised taking evidence for an unusual one-dimensional many-body state exclusively from the observation of a pseudogap.