Surface characterization of metallic molecular organic thin films: tetrathiafulvalene tetracyanoquinodimethane

The electronic structure of ex situ grown highly oriented thin films of the quasi-1D organic metal tetrathiafulvalene tetracyanoquinodimethane (TTF–TCNQ) has been characterized by means of temperature-dependent high-resolution angle-resolved photoemission spectroscopy and X-ray photoelectron spectroscopy. Band dispersion near the Fermi level (EF) is observed at low temperatures (∼100 K) for as-received samples. At room temperature both charged and neutral TCNQ species (TCNQ− and TCNQ0, respectively) coexist at the surface. The presence of TCNQ0, partly due to surface thermal vibrations, is reduced at lower temperatures because of the smaller surface oscillation amplitudes.