Development of a calibration method for quantitative x-ray powder diffraction of size-segregated aerosols.

摘要

X-ray power diffraction (XPD) is an important tool for the chemical characterization of atmospheric aerosol samples particularly when combined with elemental analysis obtained from x-ray fluorescence (XRF) measurements of the same specimen. The present study focuses on evaluating potential problems associated with XPD analysis of thin layers of particles collected on membrane filters such as would be the case for atmospheric aerosol samples and certain other classes of environmental and geological samples. These samples differ from those previously investigated in quantitative XPD in that absorption effects are minimized but particle size and preferential alignment artifacts may be more significant. The current US Environmental Protection Agency (EPA) aerosol monitoring programs emphasize the use of sampling devices which collect size-segregated aerosols of aerodynamic equivalent diameter less than 10 (mu)m. The approach used in the present experiments is to prepare thin deposits of size-segregated particles and compare the extent to which conventional thin film XRF calibration methods can be applied to quantitative XPD analysis. 13 refs., 1 fig., 7 tabs.