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Accession Number DE2012-1052160
Title High-Pressure Atomic Force Microscope for Imaging in Supercritical Carbon Dioxide.
Publication Date 2011
Media Count 8p
Personal Author A. S. Lea K. G. Knauss K. M. Rosso S. R. Higgines
Abstract A high-pressure atomic force microscope (AFM) that enables in situ, atomic scale measurements of topography of solid surfaces in contact with supercritical CO2 (scCO2) fluids has been developed. This apparatus overcomes the pressure limitations of the hydrothermal AFM and is designed to handle pressures up to 100 atm at temperatures up to approx. 350 K. A standard optically-based cantilever deflection detection system was chosen. When imaging in compressible supercritical fluids such as scCO2, precise control of pressure and temperature in the fluid cell is the primary technical challenge. Noise levels and imaging resolution depend on minimization of fluid density fluctuations that change the fluid refractive index and hence the laser path. We demonstrate with our apparatus in situ atomic scale imaging of a calcite (CaC03) mineral surface in scCO2; both single, monatomic steps and dynamic processes occurring on the (101 approx. 4) surface are presented. This new AFM provides unprecedented in situ access to interfacial phenomena at solid-fluid interfaces under pressure.
Keywords Calcites
Carbon dioxide
Fluid density
High pressure
Imaging resolution
Noise levels

Source Agency Technical Information Center Oak Ridge Tennessee
NTIS Subject Category 48F - Geology & Geophysics
48A - Mineral Industries
99F - Physical & Theoretical Chemistry
Corporate Author Wright State Univ., Dayton, OH. Dept. of Chemistry.
Document Type Technical report
Title Note N/A
NTIS Issue Number 1306
Contract Number DE-AC02-05CH11231

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