Using first-principles calculations and angle-resolved photoemission, we show that the spin-orbit interaction leads to a strong splitting of the surface state bands on low-index surfaces of Bi. The dispersion of the states and the corresponding Fermi surfaces are profoundly modified in the whole surface Brillouin zone. We discuss the implications of these findings with respect to a proposed surface charge density wave on Bi(111) as well as to the surface screening, surface spin-density waves, electron (hole) dynamics in surface states, and to possible applications to the spintronics. Recently, spin-orbit coupling (SOC) on surfaces and the resulting splitting of the surface-state bands has attracted considerable attention. While it is a wellestablished fact that the reduction of coordination at surfaces and in thin films can lead to pronounced magnetic effects, the discovery of a small splitting in the band of the sp surface state on the non-magnetic Au(111) surface and its interpretation as being due to SOC by LaShell et al.[1] came as a surprise. More sophisticated angleresolved photoemission (ARPES) investigations and calculations have meanwhile confirmed this splitting [2] and the combination of the experimental results with firstprinciples calculations do indeed proof that the SOC is causing it [2,3]. Later, larger SOC-induced splittings were found on the Li-covered surfaces of W and Mo [4] and the predicted difference in spin-orientations for H on W(110) was confirmed experimentally using spinresolved ARPES [5]. Since these surface states contribute only very little to the density of states at the Fermi level, the observed spin-orbit or Rashba splitting of these states will not show up in transport phenomena. On the other hand, surface states of a semimetal would give a prominent contribution [6,7] which could make these systems interesting for applications in the field of spintronics. The surfaces of the semimetal Bi seem to be ideal to advance our understanding of SOC on surfaces and how it manifests itself in experiments. Of particular interest are the influence of the SOC on the electron-phonon coupling [8], electron and hole dynamics [9], and the possible formation of surface charge (spin) density waves. The occurrence of strong SOC in low-dimensional structures of non-magnetic materials could also have applications like spin-filter devices. ARPES measurements of the Fermi surface (FS) andsurface states were recently performed by Ast and Höchst for Bi(111) [10]. They interpreted the obtained FS in terms of two different surface bands which are not degenerate at theΓ point. Based on this electronic structure they proposed a possible mechanism for the formation of surface charge density waves (CDW) on Bi(111) [11]. Agergaard et al. [7] measured surface states and the FS on Bi(110). They pointed out that these surface states should be completely non-degenerate because of spin-orbit splitting but, as we show below, the splitting is so large that an easy identification of the spin-split bands was not possib...

A comparative study on the adsorption of buthanedithiol (BDT), hexanedithiol (HDT), and nonanedithiol (NDT) on Au(111) from ethanolic and n-hexane solutions and two different preparation procedures is presented. SAM characterization is based on reflection-absorption infrared spectroscopy, electrochemistry, X-ray photoelectron spectroscopy, and time of flight direct recoil spectroscopy. Results indicate that one can obtain a standing-up phase of dithiols and that the amount of the precursor lying-down phase decreases from BDT to NDT, irrespective of the solvent and self-assembly conditions. A good ordering of the hydrocarbon chains in the standing-up configuration is observed for HDT and NDT when the system is prepared in degassed n-hexane with all operations carried out in the dark. Disulfide bridges at the free SH terminal groups are formed for HDT and to a lesser extent for NDT prepared in ethanol in the presence of oxygen, but we found no evidence of ordered multilayer formation in our experiments. No disulfides were observed for BDT that only forms the lying-down phase. Our results demonstrate the key role of the chain length and the procedure (solvent nature and oxygen presence) in controlling the surface structure and chemistry of SAMs dithiols on Au(111).