Anchoring of organic molecules on Cu(001) surface through S-headgroup. P. Monachesi Dipartimento di Fisica, Università dell'Aquila and INFM, L'Aquila (Italy) L. Chiodo Dipartimento di Fisica, Università di Roma, `Tor Vergata' and INFM, Roma (Italy) F. Bussolotti Dipartimento di Fisica, Università di Modena and INFM CRS-S3, Modena (Italy) M. G. Betti Dipartimento di Fisica, Università di Roma, `La Sapienza’ and INFM CRS-SOFT, Roma (Italy) C. Mariani Dipartimento di Fisica, Università di Roma, `La Sapienza’ and INFM CRS-S3, Roma (Italy) ABSTRACT We characterize, experimentally and theoretically, the electronic properties of the S/Cu(001) interface in two molecule-metal systems, Mercaptobenzoxazole (MBO) and Methanethiol on Cu(001), containing the S-headgroup. The S atom realizes the anchoring of the whole molecule to the substrate through the formation of an S-Cu hybrid, irrespective of the p(2×2) and c(2×2) reconstruction, but with different relative orbital contributions. This behaviour may be highlighted only by the comparison of the high resolution angular resolved photoemission spectra with the ab inito calculated electronic density of states of the interface. INTRODUCTION Gold, Silver and Copper surfaces are optimal substrates for self assembled molecules (SAM’s) employed in nanotechnology. Organic molecules, like thiols and thiol-like, contain Sulfur atom as a headgroup providing the primary adsorption mechanism on the substrate. This picture of Sulfur has been pointed out by several structural and electronic structure studies and agrees with that of the Anderson-News model [1] predicting the formation of bonding and antibonding states essentially between S s-p and Cu d states. Very recents high resolution angular resolved photoemission (HR-ARUPS) experiments on MBO/Cu(001) [2], that orders p(2×2), and theoretical calculations of the electronic properties of the S/Cu(001) p(2×2) system [3], have confirmed the anchoring properties of S to the substrate and, most interestingly, have allowed for the identification of the energy dispersion of the S-Cu hybrids forming at the molecule-metal interface. Since several thiols and thiol-like with S headgroup [4,5] adsorbed on Cu(001), e.g. CH 3 SH [6 ,7], undergo other reconstructions depending on coverage and temperature, we address here the question of how the anchoring properties of the S atom are affected by the reconstruction and/or by the molecule tail. We focus on two reconstructions, namely p(2×2) and c(2×2), occurring in the systems MBO/Cu(001) , CH 3 SH/Cu(001) and also in S/Cu(001). We present results of electronic structure calculations of the latter system in both reconstructions and compare them with the HR-ARUPS results obtained for MBO and CH 3 SH on Cu(001). The p(2×2) superstructure is the most stable adsorption configuration for S/Cu(001), at 0.25 ML[8,9]. It also occurs in the two system of interest here, namely, CH 3 SH (at low coverage and RT) and MBO on Cu(001). The c(2×2) structure occurs in CH 3 SH (at low coverage and low Mater. Res. Soc. Symp. Proc. Vol. 872 © 2005 Materials Research Society J2.2.1