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

TL;DR

This paper thoroughly characterizes the surfaces and electronic structures of organic quasi-one-dimensional charge transfer salts TTF-TCNQ and (TMTSF)2PF6, highlighting the importance of surface effects in interpreting photoemission spectra.

Contribution

It demonstrates the use of x-ray induced photoemission spectroscopy as a non-destructive tool and emphasizes the need for caution when interpreting one-dimensional signatures in spectra.

Findings

Surface effects can significantly influence photoemission spectra.

Generic one-dimensional signatures may be affected by surface conditions.

Caution is needed when identifying many-body states from pseudogap observations.

Abstract

We have thoroughly characterized the surfaces of the organic charge-transfer salts TTF-TCNQ and (TMTSF)2PF6 which are generally acknowledged as prototypical examples of one-dimensional conductors. In particular x-ray induced photoemission spectroscopy turns out to be a valuable non-destructive 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.