Electron Probe Measurements of Evaporated Metal Films

Calibration curves of X-ray intensity vs specimen thickness have been prepared for the electron probe microanalyzer by using evaporated films of Cr, Mn, Zn, and Au in the 0–5000 A range. For each element, the x-ray intensity increased almost linearly with thickness; for a given thickness, the x-ray intensity increased (but not linearly) with atomic number. Using previously published data on electron excitation efficiency to calculate expected x-ray intensities, the measured values from Cr, Mn, and Au were about 0.75 to 0.85 times the calculated value whereas Zn was about 1.25 times the calculated value. The variations are thought to result from some undetermined parameter such as density or internal strain.