Influence of adsorbate-substrate interaction on the local electronic structure ofC60studied by low-temperature STM

Abstract

Low coverages of C 60 on Cu͑111͒ and K/Cu͑111͒ have been investigated by scanning tunneling microscopy and spectroscopy at 10 K. By combining topographic imaging and mapping of the spectral intensity (dI/dV), we have analyzed the evolution of the t 1u -derived ͓lowest-unoccupied molecular orbital ͑LUMO͔͒ electronic states resulting from the difference in adsorption geometry on Cu͑111͒ as well as the difference in bonding when the substrate is precovered by a K monolayer. The spatial distribution and the spectral width of the LUMO-derived states are observed to be particularly sensitive to the adsorbate-substrate interaction.

Spatially resolved conductance of oriented C60

“…The spectra recorded from molecules with identical orientations did not depend on orientations of the nearest neighbour molecules. The assignment of the HOMO, LUMO, LUMO + 1, and LUMO + 2 to spectral signatures shown in figure 2(a) is based on published results [7,16]. The orbital energies of both C 60 types are summarized in table 1.…”

“…The resulting molecule-substrate interface geometry is different for bright and dim C 60 molecules and is expected to be the origin of the modifications of the molecular orbitals. Silien et al [7] have reported orbital shifts for different C 60 adsorbed on Cu(111). Here, the orientation of the C 60 is deduced from the STM image, but no statement about the adsorption sites are provided.…”

“…Therefore, scanning tunnelling microscopy (STM) and spectroscopy experiments have been performed on C 60 on various surfaces (see, for instance, [4] and references therein). These studies have shown that different adsorption geometries-orientation and adsorption site-as well as intermolecular interactions affect the C 60 electronic properties [5]- [7]. However, the respective roles of these parameters have not been disentangled and no direct relation between a single parameter and the electronic structure of individual molecules has been reported for C 60 adsorbed on noble metal surfaces.…”

Bistable Organic Memory Device with Gold Nanoparticles Embedded in a Conducting Poly(N-vinylcarbazole) Colloids Hybrid

“…The occurrence of a new gap state can be easily inferred from the previous experimental result in which energy levels of organic molecules (C 60 ) due to their chemical interaction with the metal support were modified. 35 Conversely, the influence of the molecules on the electronic structure of the metal electrode such as a reduced DOS near the Fermi level (E F ) has been predicted for various metals (Au, Pd, and Ru) with submonolayer coverages of sulfur [36][37][38] or nitrogen due to strong bond interaction between Au-S or Pd-N 39 on the basis of DFT calculations. The transferred electrons are re-distributed to relax the Coulomb energy and generate new gap states by filling the originally unoccupied states of PVK.…”

Scanning Tunneling Spectroscopy of Individual PbSe Quantum Dots and Molecular Aggregates Stabilized in an Inert Nanocrystal Matrix

“…The combination of STM and STS has already proved very useful in probing the geometry and electronic structure of individual atoms and molecules and molecular aggregates at the atomic scale. [6][7][8][9][10][11][12] Furthermore, these techniques have been successfully used for the investigation of individual InAs, CdSe, and PbSe QDs, [13][14][15][16][17] as well as their twodimensional arrays. 18,19 In order to study a single, isolated QD or small aggregates of QDs with STM, they have to be immobilized on a conducting substrate.…”