Room-temperature surface structure of 4-aminobenzoic acid on Cu(110) surfaces

The room-temperature adsorption of 4-aminobenzoic acid on a Cu(110) surface is studied with high-resolution electron energy-loss spectroscopy (HREELS), low-energy electron diffraction (LEED), temperature-programmed desorption and scanning tunnelling microscopy. Initially, the molecule adsorbs in a flat-lying geometry and forms domains with a periodicity of (3 x 4g). Increasing the coverage, the surface is saturated with this flat-lying structure at a coverage of 0.167 ML. Further increasing the surface coverage, the HREEL spectrum shows some additional upright species without any change in LEED pattern. Scanning tunnelling microscopy shows that this upright species is present along domain boundaries that are preferentially aligned along the (3, +/-4) directions. Copyright (C) 2001 John Wiley & Sons, Ltd.