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X-RAY EMISSION ANALYSIS: SAMPLE LOSSES DURING EXCITATION
Citation:
Shaw, Jr., R. AND R. Willis. X-RAY EMISSION ANALYSIS: SAMPLE LOSSES DURING EXCITATION. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-78/169 (NTIS PB80184286).
Description:
Many samples of atmospheric aerosols and biological materials containing volatile or unstable species are now being examined by X-ray emission analysis, and loss of these species by sample heating is a critical consideration. The amount of heat energy deposited in a sample by the various modes of excitation may vary by orders of magnitude. For example, if one were looking for sulfur in 1-micrometer particles of (NH4)2SO4, and using projectiles at typical operating energies (10-keV electrons or 3-MeV protons) as a means of excitation, about 1000 keV of energy would be deposited per sulfur K-shell ionization produced; while photons of energy 8-keV (using Cu K(alpha)) would deposit only about 5-keV for each K shell ionization. This paper presents calculations of energy dissipation and sample heating and loss of Al, Cu, Au, PbBrCl and (NH4)2SO4 under typical operating conditions.