EPMA of porous media: A Monte Carlo approach

We examine the influence of the sample porosity on the X-ray emission from mesoporous alumina bombarded with kilovolt electrons. Experimental results show that there is a loss of X-rays (Al K alpha and O K alpha) from those s amples when compared to a fully dense mono-crystalline alumina (sapphire), which depends on the X-ray line, the measurement time and the embedding med ium, Both geometrical and charging effects may be responsible for this sign al loss. Monte Carlo simulations of the X-ray intensity emitted from porous alumina, using different models to describe sample porosity, show that the geometrical effect of porosity itself cannot account for the X-ray loss. C harge trapping effect and/or its combination with porosity is therefore exp ected to be the major cause of the signal loss.