Highly Oriented Pyrolytic

Because STM measures a quantum-mechanical tunneling current, the tip must be within a few A of a conducting surface. Therefore any surface oxide or other contaminant will complicate operation under ambient conditions. Nevertheless, a great deal of work has been done in air, liquid, or at low temperatures on inert surfaces. Studies of adsorbed molecules on these surfaces (for example, liquid crystals on highly oriented, pyrolytic graphite ) have shown that STM is capable of even atomic resolution on organic materials. 

The actual utility of this discovery depends on the ability to go from hosts consisting of expensive, highly oriented, pyrolytic graphite to hosts composed of cheap graphite powders or fibers. Care must be taken on intercalation, because defects in such low-rank graphites may affect not only the intrinsic conductivity of the host (Z4) but may also serve as sites for oxidative reactions that may disrupt the host (Ell). 

FIG. 16 Current versus bias voltage for a CdS nanoparticle on the end of an STM tip. The CdS particles were formed by exposing a bilayer of cadmium arachidate on the STM tip to H2S gas. The other conducting surface is a highly oriented pyrolytic graphite electrode. The inset is a plot of differential conductance versus the bias voltage. (Reproduced with permission from Ref. 202. Copyright 1996 National Academy of Sciences, U. S. A.)... 

FIG. 18 Scanning force microscopy images, (a) C60 transferred horizontally onto highly oriented pyrolytic graphite (HOPG) at 25 mN m. (b) 1 1 mixed film of C60 and arachidic acid transferred horizontally onto HOPG at 25 mN m. (Reproduced with permission from Ref. 235. Copyright 1996 American Chemical Society.)... 

Fig. 9a,b. The molecular images of the monoclonal IgM on a cleaved highly orientated pyrolytic graphite (HOPG) smdace and schematic representation of the images for IgM. A flat pentagram (a) and a smaller object with higher center (b)... 

Savinova ER, Lebedeva NP, Simonov PA, Kryukova GN. 2000. Electrocatalytic properties of platinum anchored to the surface of highly oriented pyrolytic graphite. Russ J Electrochem. 36 (9) 952-959. 

Fig. 25 STS curves (normalized I/V plots of LB monolayers of isomers 55 (crosses) and 56 (dots), deposited on an Au film over HOPG (highly oriented pyrolytic graphite), and scanned with a Pt/Ir nanotip. The films exhibit rectification in opposite quadrants of the plot, where the polarity is defined by the sign of the substrate electrode. Electron flow at forward bias in each case is from the acceptor to the donor [127]...

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