Measuring the thickness of aluminium alloy thin foils using electron energy loss spectroscopy

Combining electron energy loss spectroscopy and convergent beam electron di ffraction measurements, we have determined the mean-free-path for inelastic electron scattering for four different aluminium alloys. Electron energy l oss spectroscopy spectra were acquired with the transmission electron micro scope in image mode, without any objective aperture inserted. The value for pure aluminium was determined as 119 +/- 5nm at an incident electron energ y of 150keV. For the most common alloys with moderate amounts of alloying e lements, no significant changes in the mean-free-path values are measured w ithin the 5% accuracy of the method. The-mean-free path values are required for accurate determination of the thickness of thin foils for transmission electron microscopy using electron energy loss spectroscopy On the basis o f our experimental results, we estimate a single measurement of foil thickn ess to have an accuracy of better than 8% if the mean-free-path is known wi thin 5%. The outlined procedure for thickness measurements is very robust, with thickness results being insensitive to experimental details such as in clination of the specimen or diffracting conditions. (C) Elsevier Science I nc., 2000. All rights reserved.