Coverage dependence of the structure of tetracene on Ag(110)

Abstract

The ordered adsorption structures of tetracene on Ag(110) have been studied by low energyelectron diffraction (LEED), scanning tunneling microscopy (STM) and density functionaltheory (DFT) calculations. At a low coverage, as calibrated with LEED, bothp(4 × 4) and c(8 × 4) ordered structures are simultaneously formed on an Ag(110) surface at roomtemperature. STM images suggest the molecular plane is parallel to the Ag surfacewith its long molecular axis aligned along the [001] azimuth. DFT optimizationreveals a separation of 0.3 nm between the molecular plane and substrate surfacewhile the center of the tetracene molecule is on the long bridge site. Increasingcoverage slightly, a structure is formed while the adsorbed molecules maintain the flat-lying geometry withadjacent molecules alternating their height relative to the surface.