Carbon studies by scanning probe microscopy
Applications of in situ and ex situ scanning probe microscopy (SPM) are described. Scanning probe microscopic methods are based on monitoring the interaction between a tip and substrate. SPM has been used to study various aspects of carbon behavior, including modification of the highly-oriented pyrolytic graphite (HOPG) surface and its users as an electrode. The surface morphology of other forms of carbon, such as carbon black, carbon fibrils, and coal are also studied. Pit formation by thermal gasification of HOPG occurs by a nucleation and lateral growth mechanism. Effects of different surface treatments on pit nucleation are studied by SPM and other methods for reproducible pit production. Characterization of surface properties on the basal and edge planes show effects of thermal treatment. Measurements of the monolayer pit depth show variation with experimental conditions. The electrodeposition and stripping of lead on pitted HOPG has been studied by in situ and ex situ scanning tunneling microscopy (STM) and in situ atomic force microscopy (AFM). Pb deposits preferentially formed at step and pit edges and resembles crystallite growth on a microelectrode disk. The author discusses effects of tip potential on deposition during in situ STM. After stripping, scanning microscopy and XPS indicated that residual Pb species remained on the surface. The selective etching of recessed features of various shapes in HOPG in air was accomplished using STM. Etching of the surface was restricted to the scan area and only occurred with positive biases. Lines with widths as small as 10 nm and squares 25 [times] 25 nm could be formed with monolayer depth (0.34 nm) in the HOPG. Electrochemical STM was used to study in situ the early stages of polyaniline film growth on pitted HOPG. The mechanism of polymerization was studied using three different potential schemes. A growth mechanism for polyaniline on an HOPG electrode is proposed.
- Research Organization:
- Texas Univ., Austin, TX (United States)
- OSTI ID:
- 7103186
- Country of Publication:
- United States
- Language:
- English
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Formation of monolayer pits of controlled nanometer size on highly oriented pyrolytic graphite by gasification reactions as studied by scanning tunneling microscopy
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360602* -- Other Materials-- Structure & Phase Studies
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201 -- Chemical & Physicochemical Properties
CARBON
CARBON BLACK
CARBON FIBERS
CARBONACEOUS MATERIALS
COAL
ELEMENTAL MINERALS
ELEMENTS
ENERGY SOURCES
FIBERS
FOSSIL FUELS
FUELS
GRAPHITE
MATERIALS
MICROSCOPY
MINERALS
NONMETALS
SURFACE FINISHING
SURFACE PROPERTIES
TUNNEL EFFECT