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August 18, 2009

Microscopy Today July 2009

Two articles in the recently renovated Microscopy Today are worth your time to read.

First is application of SEM/EDS to archaeology on Page 28. It presents two case studies where ancient paints are analyzed using SEM and EDS. The second case study has an interesting observation on using the ratio of Pb M(beta) to Pb M(gamma) x-ray lines to possibly discriminate lead oxides from lead carbonates (which is kind of a big deal).

Second is an overview of how beam deceleration is used to improve low accelerating voltage imaging in non-FE SEMs.

June 10, 2009

Optimizing Electron Backscatter Diffraction of Carbonate Biominerals—Resin Type and Carbon Coating

Alberto Pérez-Huertaa1 c1 and Maggie Cusacka1
a1 Department of Geographical and Earth Sciences, University of Glasgow, G12 8QQ Glasgow, UK

Abstract

Electron backscatter diffraction (EBSD) is becoming a widely used technique to determine crystallographic orientation in biogenic carbonates. Despite this use, there is little information available on preparation for the analysis of biogenic carbonates. EBSD data are compared for biogenic aragonite and calcite in the common blue mussel, Mytilus edulis, using different types of resin and thicknesses of carbon coating. Results indicate that carbonate biomineral samples provide better EBSD results if they are embedded in resin, particularly epoxy resin. A uniform layer of carbon of 2.5 nm thickness provides sufficient conductivity for EBSD analyses of such insulators to avoid charging without masking the diffracted signal. Diffraction intensity decreases with carbon coating thickness of 5 nm or more. This study demonstrates the importance of optimizing sample preparation for EBSD analyses of insulators such as carbonate biominerals.

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