Microcharacterization of trace elemental distributions within individual coal combustion particles using secondary ion mass spectrometry and digital imaging
Secondary ion image depth profiling is developed for application to the chemical characterization of individual micrometer-sized particles, specifically coal combustion fly ash collected by cascade impaction. A digital imaging system interfaced to a Cameca IMS-3F ion microscope permits the simultaneous acquisition of spatially resolved mass spectral data for a number of single particles. Small regions within each particle are chosen for computer-reconstructed local area depth profiles to minimize complications of particle geometry on sputter rate and useful ion yield. Sputtering rates are calibrated by use of SiO/sub 2/ standards and correlative SEM observation of the sputtered particles. Ion intensities averaged over groups of particles are related to concentrations by use of NBS standard fly ash samples. Substantial differences are often found in the relative concentrations and/or depth profiles of selected elements (Ba, Pb, Si, Th, Ti, U) from particle to particle. The technique is highly sensitive to trace elements within microvolumes. For example, the estimated U detection limit corresponds to approximately 10/sup 4/ atoms in an analytical volume of 0.1 ..mu..m/sup 3/ within a 20-..mu..m/sup 3/ single particle.
- Research Organization:
- Univ. of North Carolina, Chapel Hill
- OSTI ID:
- 6316009
- Journal Information:
- Anal. Chem.; (United States), Journal Name: Anal. Chem.; (United States) Vol. 59:17; ISSN ANCHA
- Country of Publication:
- United States
- Language:
- English
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37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400101 -- Activation
Nuclear Reaction
Radiometric & Radiochemical Procedures
ACTINIDES
AEROSOL WASTES
ALKALINE EARTH METALS
ASHES
BARIUM
CARBONACEOUS MATERIALS
CHEMICAL ANALYSIS
CHEMICAL REACTIONS
COAL
COMBUSTION
DATA
DIGITAL SYSTEMS
ELEMENTS
ENERGY SOURCES
EXPERIMENTAL DATA
FLY ASH
FOSSIL FUELS
FUELS
IMAGE PROCESSING
INFORMATION
ION MICROPROBE ANALYSIS
LEAD
MASS SPECTROSCOPY
MATERIALS
METALS
MICROANALYSIS
NONDESTRUCTIVE ANALYSIS
NUMERICAL DATA
OXIDATION
PARTICLE SIZE
PROCESSING
QUANTITATIVE CHEMICAL ANALYSIS
RESIDUES
SEMIMETALS
SILICON
SIZE
SPECTROSCOPY
THERMOCHEMICAL PROCESSES
THORIUM
TITANIUM
TRACE AMOUNTS
TRANSITION ELEMENTS
URANIUM
WASTES