Geometric and electronic structure of aC60monolayer on Ag(100)

Abstract

Using scanning tunneling microscopy and spectroscopy and first principles calculations, we have systematically studied the morphological and electronic structures of a C 60 monolayer on Ag͑100͒. Our results reveal that the bright-dim contrast has a definite geometric origin and there are two types of dim C 60 molecules, one a monomer and the other a dimer. With distinctive electronic properties and distinctive charge transfers in the differently adsorbed C 60 molecules, this C 60 monolayer is highly inhomogeneous and aperiodic.

Self-assembly and ordering of C60 on the WO2/W(110) surface

“…The parallel orientation of the C 60 on the WO 2 /W(110) surface indicates that the moleculesubstrate interaction is strong enough to align the molecules at low temperature, when their movement is suppressed. Similar parallel orientation of the C 60 molecules has been previously observed on certain other surfaces by low-temperature STM [25,26,28,32,33]. It is noted that STM images exhibiting three molecular lobes within an individual C 60 molecule have been acquired at a sample bias in the range from +0.7 V to +1.0 V (+0.9 V in Fig.…”

“…STM is a highly local technique that has become a powerful tool for studying the adsorption geometry and the conformation and dynamics of single organic molecules and molecular assemblies on conducting substrates [1][2][3][4][5][6][7][8][9][10]. Over the last decade STM has been used intensively for the study of C 60 self-assembled layers on a variety of metal [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36] and semiconductor [18,[37][38][39][40][41] surfaces. On most surfaces fullerene molecules self-assemble into close-packed monolayers with a hexagonal or quasi-hexagonal structure and a moleculemolecule separation close to 1 nm, as observed in bulk C 60 [18, 21-25, 27-38, 41].…”

Survey of structural and electronic properties of C60 on close-packed metal surfaces

“…The symmetry analysis also applies to fcc(100) surfaces with a 4-fold rotation symmetry: the adsorption with 2-fold symmetry (C-C bond down) matches the substrate symmetry best and is most observed in experiments [22,23,25,26,36,62]. Although the symmetry analysis from Fig.…”

“…DFT-based calculations give additional access to this important and complementary information by providing not only detailed atomic structure but also electronic properties of the substrate-adsorbate interaction, which can be compared with the various experimental observations to help us determine and understand the final structure. Indeed, it has been demonstrated that the combination of DFT with STM and/ or diffraction methods is a very efficient and accurate approach to determining C 60 monolayer properties [5,19,[29][30][31][35][36][37].…”

“…Structures containing several or many inequivalent molecules per supercell (i.e., molecules in different adsorption configurations) will be discussed as well, although their interface structure is generally less well known [19,[42][43][44][45]. The well-ordered monolayer phases usually must be prepared experimentally at higher temperatures or through sufficient post-growth annealing, which could induce not only interface reconstruction, but also polymerization or even decomposition of the C 60 molecules [36,40,46], and this aspect will also be discussed (note that there may be unreconstructed structures before such annealing, e.g., for C 60 on Cu(111), even though there is no detailed structure determination for these [41]). Investigating the interfacial atomic structure is very important since the structural details determine electronic and the transport properties [26][27][28][29]47], which will also be addressed.…”