Surface characterization of metallic molecular organic thin films: tetrathiafulvalene tetracyanoquinodimethane

The electronic structure of ex situ grown highly oriented thin films of the quasi-ID organic metal tetrathiafulvalene tetracyanoquinodimethane (TTF-TC NQ) has been characterized by means of temperature-dependent high-resolutio n angle-resolved photoemission spectroscopy and X-ray photoelectron spectro scopy. Band dispersion near the Fermi level (EF) is observed at low tempera tures (similar to 100 K) for as-received samples. At room temperature both charged and neutral TCNQ species (TCNQ(-) and TCNQ(0), respectively) coexis t at the surface. The presence of TCNQ(0), partly due to surface thermal vi brations. is reduced at lower temperatures because of the smaller surface o scillation amplitudes. (C) 2001 Elsevier Science B.V. All rights reserved.