Monte Carlo analysis of the detection of clay occlusion of respirable quartz particles using multiple voltage scanning electron microscopy

Abstract

Summary:The electron incident-energy dependence of the relative intensities of Al and Si x-rays produced in a respirable-sized quartz particle by scanning electron microscopy is sensitive to the inhomogeneity of the distribution of Al and Si in the particle. Realistic Monte Carlo calculations of this energy dependence validate the proposal to use this effect for the detection of particles in which an aluminosilicate coating occludes the surface of a silica core.

Risk of silicosis in cohorts of Chinese tin and tungsten miners and pottery workers (II): Workplace-specific silica particle surface composition

“…For silicates, the depth of electron excitation of X-rays decreases from several micrometers by 20 keV electrons to the order of a tenth of a micrometer for 5 keV electrons. Then the elemental spectra ratio of Si/(SiþAl) obtained at the two electron beam voltages in an SEM-EDS analysis can be compared to distinguish clay occlusion of a silica particle surface from homogeneous composition, since most clay compositions are approximately equi-atomic percent silicon and aluminum Harrison et al, 1997;Hnizdo and Wallace, 2002].…”