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We investigated the spin properties of the terbium phthalocyanine (TbPc) species adsorbed on the superconductor NbSe

We investigated the reduction of a CeO2(111) surface after the deposition of size-selected Pt8 clusters on it via x-ray photoelectron spectroscopy (XPS). Electron transfer from Pt to CeO2(111) results in the reduction of Ce4+ to Ce3+ and the subsequent formation of Ptδ+ atoms at the interface. We quantitatively estimated the reduction from the Ce3+/(Ce3+ + Ce4+) ratio determined from the Ce3d spectra. Approximately 30% of Ce4+ under or in the perimeter of the Pt8 cluster was reduced to Ce3+. The XPS spectra showed an increase in the ratio of Ce3+/(Ce3+ + Ce4+) with an increase in the amount of Pt8 clusters deposited on the CeO2(111) surface. The reduction of 3.7 Ce4+ to Ce3+ per Pt8 clusters, followed by the formation of 3.7 Ptδ+ atoms per Pt8 clusters was observed at 0.006 ML (mono layer) Pt coverage. The actual Ce3+ formation influenced by Pt deposition was approximately 2.5%. We estimate that approximately 30% of Ce4+ under or in the perimeter of a Pt8 cluster was reduced to Ce3+. At a higher coverage of 0.015 ML, the reduction of 2.2 Ce4+ to Ce3+ per Pt8 cluster, followed by the formation of 3.2 Ptδ+ atoms per Pt8 cluster was observed. This implies the aggregation of Pt clusters occurred at a higher Pt coverage. Atomically precise quantification of the electron transfer across the Pt–CeO2(111) interface can enable an improved understanding of the metal-support interaction.

In this study, graphene oxide (GO) sheets produced in the form of stable aqueous dispersions were deposited on Au (111), freshly cleaved mica, and highly oriented pyrolytic graphite (HOPG) substrates. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) were used to study the presence and distinct contact of GO sheets on the substrates. It was revealed from the topography images that high-quality ultraflat GO monolayer sheets formed on the substrates without distinct cracking/wrinkling or folding. GO sheets with apparent height variation observed by microscopy also indicate ultraflat deposition with clear underlying steps. It was observed that ultrasonication and centrifuge steps prior to deposition were very effective for getting oxidation debris (OD)-free ultraflat single monolayer GO nanosheets onto substrates and that the process depends on the concentration of supplied GO solutions.

We investigate the atom-specific interfacial electronic properties of the epitaxial graphene on Si-terminated SiC substrate using density functional theory (DFT) calculation with van der Waals interaction correction, focusing on the dependency of the local electronic state on the chemical environment. The band structure projected on the respective atomic orbitals of the carbon atoms in the buffer layer and uppermost Si atoms demonstrates that the dangling bonds of these atoms form band structures around the Fermi level. The contribution of each atom to the dangling bond states strongly depends on the chemical environment, i.e., the presence/absence of the interlayer Si-C covalent bond. This difference also affects the atom-specific local density of states of the top-layer graphene through its interaction with the substrate/buffer layer. We demonstrate that the bias voltage dependency of the scanning tunneling spectroscopy (STS) mapping image clearly reflects the presence of the dangling bonds of the buffer layer carbon or uppermost Si atom in the substrate, which would enable the detection of the buried dangling bond with an atomic spatial resolution via STS.

Supported Pt catalysts and ceria are well known for their application in automotive exhaust catalysts. Size-selected Pt clusters supported on a CeO

Epitaxial graphene on SiC that provides wafer-scale and high-quality graphene sheets on an insulating substrate is a promising material to realize graphene-based nanodevices. The presence of the insulating substrate changes the physical properties of free-standing graphene through the interfacial phonon, e.g., limiting the mobility. Despite such known impacts on the material properties, a complete and microscopic picture is missing. Here, we report on atomically resolved inelastic electron tunneling spectroscopy (IETS) with a scanning tunneling microscope for epitaxial graphene grown on $4H$-SiC(0001). Our data reveal a strong spatial dependence in the IETS spectrum, which cannot be explained by intrinsic graphene properties. We show that this variation in the IETS spectrum originates from a localized low-energy vibration of the interfacial Si atom with a dangling bond via ab initio electronic and phononic state calculations. This insight may help advancing graphene device performance through interfacial control.

Reduction of CeO 2 (111)/Ru(0001) surface by atomic hydrogen was investigated using scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS). We observed the formation of oxygen vacancy trimers and hydroxyl trimers on the stoichiometric CeO 2 (111) surface when it was exposed to atomic hydrogen at room temperature. The reaction of an impinging hydrogen atom with a surface oxygen atom yields a hydroxyl species, which diffuse on the surface until stabilized by the formation of OH trimers. The hydrogen atoms were located at atop sites of the oxygen atoms in the topmost surface layer. A reaction between the hopping hydrogen atom and the hydroxyl species yields a water molecule, which is desorbed from the surface leaving an oxygen defect. The oxygen vacancies were also observed as a trimer of vacancies. XPS measurements showed an increase of a reduced Ce and hydroxyl species with an amount of exposed hydrogen atoms. The former was estimated by measuring the ratio of Ce 3 + /Ce 4 + in the Ce 3d components. Our study shows the formation of hydroxyl trimer species in atomic scale upon atomic hydrogen exposure to CeO 2 (111) surface which could offer new catalytic activity.

We have observed two type of bonding configuration of Iodobenzene (C6H5I) molecule upon room temperature adsorption on the Si(111)-7×7 surface and investigated an effect of Adsorbate-Electron interaction on a bonding configuration change of the Iodobenzene molecules on the Si(111)-7×7 surface using scanning tunneling microscope (STM). With the direct-current heating, a conversion rate of the bonding configuration as a function of the lattice temperature, K(Tl), has been determined. The plot of ln(K(T)) vs. T shows a deviation from a Arrhenius straight line, which suggests that the current accelerates the molecule's reaction by heating the adsorbate preferentially above the lattice temperature. Though tunneling current induced chemical reaction has been reported, we believe this is the first report of a direct observation that the interaction between an adsorbate and lattice current causes a chemical reaction.

We formed an epitaxial film of CeO2(111) by sublimating Ce atoms on Ru(0001) surface kept at elevated temperature in an oxygen ambient. X-ray photoemission spectroscopy measurement revealed a decrease of Ce(4+)/Ce(3+) ratio in a small temperature window of the growth temperature between 1070 and 1096 K, which corresponds to the reduction of the CeO2(111). Scanning tunneling microscope image showed that a film with a wide terrace and a sharp step edge was obtained when the film was grown at the temperatures close to the reduction temperature, and the terrace width observed on the sample grown at 1060 K was more than twice of that grown at 1040 K. On the surface grown above the reduction temperature, the surface with a wide terrace and a sharp step was confirmed, but small dots were also seen in the terrace part, which are considerably Ce atoms adsorbed at the oxygen vacancies on the reduced surface. This experiment demonstrated that it is required to use the substrate temperature close to the reduction temperature to obtain CeO2(111) with wide terrace width and sharp step edges.

We demonstrate that, by using a Xe-buffer-layer-assisted deposition, a metal electrode can be formed on an organic film without altering the chemical properties of the molecules. A new efficient measurement of inelastic tunneling spectroscopy (IETS) was demonstrated by attaching the scanning tunneling microscopy (STM) tip to the Au cluster. Au electrode was formed on a Xe buffer layer condensed on an alkanethiol self-assembled monolayer (SAM), in which the Xe layer prevents direct interaction between hot metal atoms and molecules in the film. An IETS measurement executed with the new method revealed the robustness of the molecules at the metal-film interface.

The surface morphology variation of CeO2(111) with changing annealing condition was examined by scanning tunneling microscopy (STM). Hexagonal islands and pits containing two types of step edge have been found as characteristic features in a short-time-annealed surface. We observed that the triangular pits having only one type of step edge increase in number with annealing time, while the hexagonal pits and islands decrease and the deviated hexagonal pits increase. Step edges of the hexagonal pits that have higher coordinative saturation get preferential thermodynamic stability to form triangular pits, the most stable surface structures on the CeO2(111) surface in the equilibrium stage of annealing. These results have important implications for controlling catalytic activity on ceria.

We demonstrate that the electron spin resonance–scanning tunneling microscope can detect the Larmor frequency of a single spin with the atomic scale resolution on the oxygen-adsorbed Si(111)-7×7 surface. The spin signal from the Si dangling bond was detected on the oxygen-induced bright Si adatom with the Larmor frequency corresponding to g∼2.00. However, no peak was detected on the dark adatom that is tied with an oxygen atom and the dangling bond is disappeared.