Grazing-exit electron probe microanalysis (GE-EPMA) was performed for single Al2O3 and atmospheric particles, deposited on a flat Si substrate coated by gold, by using an aperture (1 mm in diameter) in front of an energy-dispersive X-ray detector. Silicon Kα X-rays from the Si substrate were strongly observed at an exit angle of approx. 45°C. However, they disappeared at grazing-exit angles about 0° and only the X-rays from particles were detected. Furthermore, Al Kα and O Kα intensities from single Al2O3 particle were enhanced approximately three- and sixfold at the grazing-exit angles (approx. 1°), respectively, in comparison with those at large angle (approx. 7°). The background intensities at the energy of Al Kα and O Kα almost monotonously decreased with decreasing exit angle. As a result, the intensity ratios of Al Kα and O Kα X-rays to the background intensities were enhanced five- and sixfold, respectively. This enhancement is considered to be caused by the interference effect of both directly detected X-rays and reflected X-rays on the flat substrate. The similar results are also obtained for Al Kα, Si Kα, K Kα and Ca Kα emitted from single atmospheric particle. The significance of the matrix effect in the particle is also pointed out.
ASJC Scopus subject areas
- Analytical Chemistry
- Atomic and Molecular Physics, and Optics