A Monte Carlo Program for Quantitative Electron-Induced X-ray Analysis of Individual Particles

Abstract

A versatile Monte Carlo program for quantitative particle analysis in electron probe X-ray microanalysis is presented. The program includes routines for simulating electron-solid interactions in microparticles lying on a flat surface and calculating the generated X-ray signal. Simulation of the whole X-ray spectrum as well as phi(z) curves is possible. The most important facility of the program is the reverse Monte Carlo quantification of the chemical composition of microparticles, including low-Z elements, such as C, N, O, and F. This quantification method is based on the combination of a single scattering Monte Carlo simulation and a robust successive approximation. An iteration procedure is employed; in each iteration step, the Monte Carlo simulation program calculates characteristic X-ray intensities, and a new set of concentration values for chemical elements in the particle is determined. When the simulated X-ray intensities converge to the measured ones, the input values of elemental concentrations used for the simulation are determined as chemical compositions of the particle. This quantification procedure was evaluated by investigating various types of standard particles, and good accuracy of the methodology was demonstrated. A methodology for heterogeneity assessment of single particles is also described.

Microscopic characterization of carbonaceous aerosol particle aging in the outflow from Mexico City

“…Electron microscopy with energy dispersive X-ray (EDX) microanalysis or electron energy loss spectroscopy (EELS) yields spatially resolved chemical composition of individual particles Katrinak et al, 1992). One general limitation of EDX is that quantitative analysis of low-Z elements (carbon, nitrogen, and oxygen) is not always possible and requires time-intensive Monte-Carlo calculations (Ro et al, 2003(Ro et al, , 2004. TEM imaging with EELS can be used to characterize carbon content of particles, but its limited energy resolution precludes detailed analysis of carbon bonding (Katrinak et al, 1992).…”

Characterisation of individual aerosol particles collected during a haze episode in Incheon, Korea using the quantitative ED-EPMA technique

“…The net characteristic X-ray intensities of chemical elements were evaluated by a nonlinear leastsquares fitting using the AXIL programme (Vekemans et al, 1994). A Monte Carlo simulation with successive approximation was used for quantification (Ro et al, 2003). The elemental quantification procedure provided results with an accuracy of within 12% relative deviations between the calculated and nominal elemental concentrations for the standard particles (Ro et al, 2000(Ro et al, , 2001.…”

Nondestructive Characterization of Municipal-Solid-Waste-Contaminated Surface Soil by Energy-Dispersive X-ray Fluorescence and Low-Z (Atomic Number) Particle Electron Probe X-ray Microanalysis

“…32 The elemental concentrations of the individual particles were determined from their X-ray intensities by the application of a Monte Carlo calculation combined with reverse successive approximations. 31,33 The quantification procedure provided results with an accuracy of within 12% relative deviation between the calculated and nominal elemental concentrations for various standard particles. 33 The low-Z particle EPMA method can provide quantitative information on the chemical compositions, and particles can be classified based on their chemical species.…”

“…31,33 The quantification procedure provided results with an accuracy of within 12% relative deviation between the calculated and nominal elemental concentrations for various standard particles. 33 The low-Z particle EPMA method can provide quantitative information on the chemical compositions, and particles can be classified based on their chemical species. The analytical procedure for determining the chemical species of individual particles and assigning those particles to specific types is described in more detail elsewhere.…”