Analytical Methods:Microprobe

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Element micro-analysis
Microprobe analysis produces element concentration data on a microscopic scale.

Questions
Microprobe analysis


 * Provenance and mineralogy
 * Material identification
 * Post-depositional soil processes (Ca-Fe-PO4)

Case studies include:
 * Micromorphological and Microchemical Analysis of St. Kilda Soils.
 * Micromorphology, image and microprobe analysis to identify black carbonaceous material in anthrosols.

Sample preparation
The samples for analysis need to be very specific as space in the electron microscope is limited and it can be hard to locate the area of interest on a large polished sample.

SEM-EDX and SEM-WDX: Polished thin sections are ideal but if semi-quantitative analysis is sufficient then powders, dried or fresh samples may be used depending on the capabilities of the electron microscope. For EDX and WDX analyses samples also need to be coated with carbon to prevent the build up of electrical charging at the surface.

No special sample preparation is needed for LA-ICP-MS, PIXIE or XRF analyses.

Analysis
A number of microanalytical systems exist; the most commonly used are SEM-EDX, SEM-WDX, PIXE, XRF and LA-ICP-MS.

Synchrotron Radiation induced X-ray analysis has also been used increasingly over the last decade. However, the cost of this high energy technique generally limits it use to research projects only. The main benefit of synchrotron radiation analysis is increased spatial resolution, its ability to provide fine structural analysis of materials and molecules, and lower element detection limits.

Data and interpretation
The type of data produced will depend on the way in which the analysis was carried out. Maps of relative element concentrations Semi-quantitative element concentrations - point and area analyses, Fully quantitative - point and area analyses with standards.

Things to remember and assumptions: Relative concentration maps % concentrations (mass or atomic)

Variability and scaling issues Interference and overlap Operating conditions Standards

Related techniques

 * Electron microscopy
 * Micromorphology / thin section analysis
 * Image analysis
 * Multi-element analysis