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Scanning Tunneling Microscope (scanning + tunneling_microscope)
Selected AbstractsMolecular Tectonics at the Solid/Liquid Interface: Controlling the Nanoscale Geometry, Directionality, and Packing of 1D Coordination Networks on Graphite SurfacesADVANCED MATERIALS, Issue 10-11 2009Artur Ciesielski Supramolecular arrays composed of 1-D coordination networks on surfaces, with nanoscale control over both the geometry and the directionality, are achieved through the design and combination of organic tectons with metal complexes (CoCl2) or metal centers (Pd(BF4)2). Scanning tunneling microscope at the solid/liquid interface allows the visualization of long and shape-persistent arrays, with either linear or zig-zag geometries. [source] Organization of Organic Molecules with Inorganic Nanoparticles: Hybrid Nanodiodes,ADVANCED FUNCTIONAL MATERIALS, Issue 5 2008Kallol Mohanta Abstract A monolayer of inorganic nanoparticles and a monolayer of organic molecules have been electrostatically assembled in sequence. Such assemblies or organizations exhibit electrical rectification. When the sequence of the organization is reversed, the direction of rectification becomes opposite. In both n-type ZnO/organic and organic/n-ZnO assemblies, electron flow is favorable from the n-ZnO nanoparticle to the (electron-accepting) organic molecule. While the individual components do not show any rectification, substitutes of the organic molecule tune electrical rectification. Junctions between a p-type ZnO nanoparticle and an electron-donating metal phthalocyanine favor current flow in the nanoparticle-to-phthalocyanine direction. The rectification in a junction between a nanoparticle and an organic molecule is due to the parity between free carriers in the former component and the type of carrier-accepting nature in the latter one. By observing electrical rectification with the tip of a scanning tunneling microscope, organic/inorganic hybrid nanodiodes or rectifiers on the molecular/nanoscale have been established. [source] Cover Picture: Fabrication and Electrical and Mechanical Properties of Carbon Nanotube Interconnections (Adv. Funct.ADVANCED FUNCTIONAL MATERIALS, Issue 11 2005Mater. Abstract The fabrication of carbon nanotube (CNT) structures, including simple tube,tube connections, crossed junctions, T-junctions, zigzag structures, and even nanotube networks, has been achieved by cutting and soldering CNTs using electron-beam-induced deposition of amorphous carbon (a-C), as detailed in the work of Peng and co-workers on p.,1825. These CNT structures have been constructed with a high degree of control, and it is found that the electric conductance and mechanical strength of the junctions can be improved by the deposition of a-C and by increasing the contact area of the junctions. Individual carbon nanotubes (CNTs) have been cut, manipulated, and soldered via electron-beam-induced deposition of amorphous carbon (a-C) and using a scanning tunneling microscope inside a transmission electron microscope. All CNT structures, including simple tube,tube connections, crossed junctions, T-junctions, zigzag structures, and even nanotube networks, have been successfully constructed with a high degree of control, and their electrical and mechanical properties have been measured in situ inside the transmission electron microscope. It is found that multiple CNTs may be readily soldered together with moderate junction resistance and excellent mechanical resilience and strength, and the junction resistance may be further reduced by current-induced graphitization of the deposited a-C on the junction. [source] Molecular rectification in metal,bridge molecule,metal junctionsPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 4 2010Yaqing Liu Abstract Molecular bridged nanocontacts allow direct electrical addressing of electroactive molecules, which is of interest for the development of molecular based electronic devices. In the present paper, the electroactive molecule 6-ferrocenyl-1-hexanethiol (Fc-HT) was integrated into metal,bridge,metal (MBM) junctions assembled in a scanning tunneling microscope (STM) setup. A diode-like behavior was observed from the current/bias (It/Vb) signal through Au (substrate)/Fc-HT/Au (tip) junction, which presented an asymmetric current response due to the resonant tunneling between metal electrode and ferrocenylthiol molecules. With gate electrode modulation, the enhancement of the tunneling current can be controlled, which allows to tune the direction of the current rectification. Our investigations demonstrated that ferrocenylthiol bridged MBM nanostructure has potential applications in the future design of higher-order heterojunctions components in combination with electrochemical logic gates. [source] Video-rate scanning probe control challenges: setting the stage for a microscopy revolutionASIAN JOURNAL OF CONTROL, Issue 2 2009M. J. Rost Abstract Scanning probe microscopy is at the verge of revolutionizing microscopy once again. Video-rate scanning tunneling microscope (STM) and video-rate atomic force microscope (AFM) technology will enable the direct observation of many dynamic processes that are impossible to observe today, such as atom or molecule diffusion, real time film growth, or catalytic reactions. In this paper we discuss the critical aspects that have to be taken into account when working on increasing the imaging speed of scanning probe microscopes. We highlight the state-of-the-art developments in the control of the piezoelectric scanning elements and describe the latest innovations regarding the design and construction of the whole mechanical loop including new scanner geometries. We identify critical aspects for which no obvious solution exists and aspects where advanced control engineering can help, like piezo non-linearities, the acceleration limit and the challenging technical requirements for the preamplifiers that are needed for measuring a tunneling current. Finally, we provide an overview of a number of new directions that are being pursued to solve the problems currently encountered in scanning probe technology. Copyright © 2009 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society [source] Vibronic Transitions in Single MetalloporphyrinsCHEMPHYSCHEM, Issue 5 2005H. J. Lee Dr. Abstract Structural and electronic properties of single zinc etioporphyrin molecules adsorbed on Al2O3/NiAl(110) were probed by a low-temperature scanning tunneling microscope (STM). Scanning tunneling spectroscopy (STS) revealed progressions of spectral features corresponding to the vibronic states of individual molecules that depend strongly on the molecular conformations. Vibronic features observed by STS were compared with the results from fluorescence induced by tunneling electrons (tunneling-induced fluorescence, TIF). [source] Study of the Electroless Silver Seed Formation on Silicon SurfaceCHINESE JOURNAL OF CHEMISTRY, Issue 2 2007Hao Tong Abstract The silver seed on silicon was prepared through aqueous HF and AgNO3 solution at room temperature. In order to explore the formation process of silver seed on silicon, the methods of open circuit potential with time (OCP- t), anodic stripping sweep voltammetry (ASV) and scanning tunneling microscope (STM) were used in this work. The procedure of silver nucleus growing into large particles was explained by electro-negativity. The growth mechanism of silver seed on silicon has been presented: at first, the silver monolayer and multilayer firstly grows onto silicon without fully covering the surface at the expense of silicon etching due to the silver seed attracting the electron from silicon, after that, the monolayer coalesces together, forming continuous grain film with some silver atoms diffusing into the silicon and the multilayer still grows thick simultaneously. [source] | |||||||||||||