Characterization of individual atmospheric particles by element mapping in electron probe microanalysis

Abstract

Abstract. In this paper procedures for the characterization of individual aerosol particles by element mapping in the electron microprobe are presented. The number, size and qualitative chemical composition of particles is derived from a combination of secondary or backscattered electron images and element distribution maps. Accuracy of the size distribution and reliability of the qualitative analysis procedure were checked with silicate samples. In order to obtain a semi-quantitative estimate of the chemical composition of individual particles the count rates taken from element distribution maps are corrected for matrix and geometric effects using particle ZAF procedures.

A method to correct defocused element distribution maps in electron probe microanalysis

“…However, we have observed noticeable defocusing at magnifications as large as 1800x in some instances. For example, we have come across Mg distribution maps of particles [5], obtained with the Mg Kc~ line and a TAP spectrometer crystal, where at magnification 1800x the intensity at locations far from the L O O F was reduced by as much as 30 %.…”

“…By 'surface' we mean a layer of thickness ~< 1 micrometer. This is of great interest in many areas of science and engineering, such as materials science, geology, and even atmospheric science, e.g., in the characterization of aerosols [5].There are two basic methods to generate an element distribution map, the beam scan method and the stage scan method. In the beam scan method, the electron beam is scanned across a rectangular region of the sample surface.…”

Optimization of experimental conditions of thin‐window EPMA for light‐element analysis of individual environmental particles

“…The problem of peak overlaps can be minimized by using wavelength-dispersive (WD) detection, which was successfully applied for particle analysis by EPMA, but only for particles insensitive to the electron beam. 4,11 As several environmental applications need the analysis of nutrient-containing particles, the beam current must be minimized and ED is the only possibility for the detection of x-rays. Therefore, substrate materials should contain as few interfering elements as possible.…”

“…In contrast, for determining possible sources of particulate air pollution or for characterizing particles suspended in water, huge numbers of individual particles have to be analysed. 4 In order to solve this analytical task, electron probe x-ray microanalysis (EPMA) is a widely applied, standardized technique, which can provide excellent possibilities for automated analysis if it is combined with evaluation procedures for huge data sets. 5 EPMA using energy-dispersive x-ray (EDX) detection with conventional semiconductor detectors has a limitation for the determination of light elements, mainly because of the low transmission of their beryllium windows for characteristic x-rays of low-Z elements (Z < 11).…”

Characterization of indoor and outdoor atmospheric pollutants impacting architectural monuments: the case of San Jerónimo Monastery (Granada, Spain)

“…There is a vast body of literature tackling the impact of outdoor and indoor air composition and microclimate on damaging our CH, in which diverse analytical techniques are applied to characterize and quantify atmospheric aerosols, such as, e.g., electron probe microanalysis (EPMA), X-ray fluorescence (EDXRF), scanning electron microscopy (SEM), ion chromatography (IC), gas chromatography-mass spectrometry (GC-MS), transmission electron microscopy (TEM), and X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and recently Raman spectroscopy (RS) (Weinbruch et al 1997;Van Grieken et al 2000;Delalieux et al 2001;Ro et al 2001;Murr and Bang 2003;Liu et al 2005;De Hoog et al 2005;Simão et al 2006;Ivleva et al 2007).…”