Quantitative elemental microanalysis of rough-surfaced soil specimens in the scanning electron microscope using a peak-to-background method

Scanning electron microscopy is very useful for morphological examination of pedofeatures. Whenever quantitative elemental microanalysis of pedofeatures has been required during such morphological examinations, either thin sections or polished resin-impregnated blocks across similar pedofeatures have had to be prepared to satisfy the smooth flat surface requirement of currently used electron microanalytical methods. This pre-requisite has been accompanied by both conceptual and technical problems. A direct method for obtaining quantitative elemental microanalyses of rough-surfaced soil specimens in the scanning electron microscope is examined here. This method is based on the use of peak-to-background ratios in energy dispersive X-ray spectra. Analysis of a pyrite standard at a range of geometrys of analysis and of the iron sulphide minerals in two Holocene sediments indicates that the peak-to-background method can be used to obtain reliable quantitative elemental compositions of rough-surfaced soil specimens in the scanning electron microscope. Under ideal operating conditions (i.e., flat, polished specimens), the peak-to-background method will not be as accurate as the currently used peak integral methods; however, the results here indicate that the peak-to-background method has, for the analysis of soil, the important advantage of being able to directly provide reliable quantitative elemental microanalyses of pedofeatures on rough-surfaced soil specimens in the scanning electron microscope.