We investigate the temperature dependence of the optical reflectance anisotropy (RA) of the Au( 110)-(1 × 2) surface and find that transitions involving surfacemodified bulk bands contribute to the RA spectrum. The RA peaks observed at room temperature at photon energies of 3.52 and 4.50 eV are assigned to the transitions E F → L u 1 and L 2 → L u 1 , respectively. The assignments are based upon a comparison between temperature-induced shifts in the energy of these RAS peaks and thermovariation optical spectroscopy results of the temperature dependence of transition energies between bands at the L symmetry point. The application of RAS to Au(110) can be seen as a model system for exploring surfaces in a range of environments including ultra-high vacuum,high pressures and at the solid/liquid interface. The results reported here further the understanding of the RA spectrum of the clean Au(110) surface.

We have investigated the adsorption of L-cysteine (L-Cys) onto Au(110) in an electrochemical cell and under ultra-high vacuum (UHV) conditions using reflection anisotropy spectroscopy (RAS). The L-Cys saturated surfaces created by both deposition methods exhibit similar RA profiles which indicates a similar adsorption process. Our results are consistent with L-Cys binding to the Au(110) surface through a goldthiolate (Au-S) linkage. Heating the L-Cys saturated surface in UHV to 580 K results in the decomposition of the adsorbate and leaves behind a sulphur/Au surface composed of different structural domains.

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By utilizing reflection anisotropy spectroscopy (RAS) and scanning tunneling microscopy (STM) measurements of the ion-bombarded Cu (110) surface at low temperatures, we have developed a simple methodology for estimating the effective surface area over which irradiation-induced defects perturb surface states, leading to a reduction in the intensity of the 2.1 eV RAS peak of this surface. Each composite defect decorating an ion-impact site quenches the RAS signal in proportion to an area equivalent to approximately 170 unit cells. We estimate that an atomic defect has an effective RAS cross section with area approximately equal to that of a circle with a radius of 0.75 nm, an area equivalent to that of around 19 unit cells. Accurate determination of the coverage and spatial distribution of surface defects is a prerequisite for a coherent analytical approach to modeling the RAS data of this system.

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The adsorption of the amino acid L-cysteine (L-Cys) onto the Ag(110) surface at room temperature is investigated using reflection anisotropy spectroscopy (RAS). The adsorption of L-Cys at metal surfaces offers a route to the immobilisation of proteins with potential applications in the nanoscale fabrication of biomaterial surfaces. L-Cys binds strongly to Ag(110) by the formation of a thiolate linkage. Heating the L-Cys saturated surface to 580 K results in the decomposition of the adsorbate, leaving a chemisorbed S adlayer with a c(8 × 2) structure.1 Introduction The self-assembly of organic molecules into thin films at material surfaces is a process that offers a flexible route to the nanoscale engineering of chemically functionalised surfaces with applications in molecular electronics, corrosion inhibition, sensors and biomaterials. The surface-sensitive linear optical technique of reflection anisotropy spectroscopy (RAS) [1][2][3], in combination with electron-based probes, has been used to monitor the growth of ultra-high vacuum (UHV) deposited molecular films and RAS has shown sensitivity to molecular orientation and assembly [4][5][6][7]. These previous RAS studies have focused on the Cu(110) substrate to induce ordered anisotropy in the growing film and have exploited molecular adsorbates that interact via the Cu-carboxylate interaction.Another molecule-substrate interaction of technological importance is the metal-thiolate bond. This interaction is exploited in the routine preparation of self assembled monolayers of alkane-thiol molecules at Au surfaces [8,9]. While the Au-thiol interaction has been well studied, relatively little is currently known about the self-assembly and bonding of thiols on other metal surfaces.In the work presented here, we investigate the adsorption of the amino acid L-cysteine (L-Cys) [HS-CH 2 -CH(NH 2 )-COOH] on Ag(110). L-Cys contains a thiol (-SH) group and is known to adsorb onto Au surfaces via a thiolate (Au-S) linkage [10]. The adsorption of L-Cys at metal surfaces offers a route to the immobilisation of proteins with potential applications in the nanoscale fabrication of biomaterial surfaces. We find evidence for L-Cys binding to the Ag(110) surface through an Ag-thiolate linkage. Heating the L-Cys saturated surface results in the decomposition of the adsorbed L-Cys and leaves behind an ordered S adlayer.

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