X-ray-diffraction characterization of Pt(111) surface nanopatterning induced by C60 adsorption

Abstract

Understanding the adsorption mechanisms of large molecules on metal surfaces is a demanding task. Theoretical predictions are difficult because of the large number of atoms that have to be considered in the calculations, and experiments aiming to solve the molecule-substrate interaction geometry are almost impossible with standard laboratory techniques. Here, we show that the adsorption of complex organic molecules can induce perfectly ordered nanostructuring of metal surfaces. We use surface X-ray diffraction to investigate in detail the bonding geometry of C(60) with the Pt(111) surface, and to elucidate the interaction mechanism leading to the restructuring of the Pt(111) surface. The chemical interaction between one monolayer of C(60) molecules and the clean Pt(111) surface results in the formation of an ordered sqrt[13] x sqrt[13]R13.9 degrees reconstruction based on the creation of a surface vacancy lattice. The C(60) molecules are located on top of the vacancies, and 12 covalent bonds are formed between the carbon atoms and the 6 platinum surface atoms around the vacancies. In-plane displacements induced on the platinum substrate are of the order of a few picometres in the top layer, and are undetectable in the deeper layers.

Optimal Electron Doping of aC60Monolayer on Cu(111) via Interface Reconstruction

“…The single adsorption site of C 60 , as determined here by LEED, was inferred previously from our STM study [8] but is at odds with an earlier STM result [18]. In C 60 =Ptð111Þ [4] and C 60 =Agð111Þ [7], a C 60 is found to reside atop a single atom vacancy, rather than a 7-atom vacancy. We also tested this unlikely single-vacancy model.…”

“…Ultimately, it is the LEED I-V analysis that confirms the r-fcc model. The 7-atom vacancy holes observed in C 60 =Cuð111Þ interface are much larger than the single-vacancy holes previously observed [4,7]. We believe the more corrugated C 60 =Cuð111Þ interface allows more intimate substrate-molecule contact and is likely the key of ''adatom self doping'' that renders C 60 optimally doped.…”

“…This raises the question of the role of the C 60 =metal interface structure. Although strong C 60 -metal interactions are not expected for, e.g., C 60 on noble metal surfaces, there is increasing evidence of C 60 -induced interface reconstruction for C 60 =Auð110Þ [3], C 60 =Ptð111Þ [4], C 60 =Alð111Þ [5], C 60 =Agð100Þ [6], and even for C 60 =Agð111Þ [7] and C 60 =Cuð111Þ [8], etc. The typical scenario is that C 60 tends to dig a ''vacancy'' in the surface.…”

Organic Molecules on Noble Metal Surfaces: The Role of the Interface

“…After annealing the fullerene bond with Pt(111) substrate become strongly covalent. The deposition of one monolayer of C 60 on the Pt(111) surface at T < 580°C leads to an ordered double domain hexagonal reconstruction, that is present also for coverages exceeding 1 ML (Pedio et al, 1999, Felici et al, 2005. The long range molecular ordening formation is a kinetically controlled process.…”

“…In spite of these minor differences, passing from 150 K to RT, there is no evidence for the appearance of two different electronic states corresponding to the two different kinds of molecules (bright and dim) observed in STM images, which may be easily explained with the occurrence of the two molecular orientation revealed by the high resolution STM images (Lu, 2003) and by XPD. We discuss two cases systems: the "covalent" C 60 /Pt(111) (Felici, 2005) with the partially "ionic" C 60 /Au(110) (Pedio et al, 2000, Hinterstein et el., 2008 systems. Fig.…”