ABSOLUTE MEASUREMENT OF NORMALIZED THICKNESS, T/LAMBDA(I), FROM OFF-AXIS ELECTRON HOLOGRAPHY

A simple method is described for determination of the quantity t/lambda(i) from off-axis electron holograms, where t is the local thickness and lambda(i) is the mean-free-path for inelastic scattering of high energy electrons. The method uses the energy-filtered amplitude reconstructed from a hologram and, when applied to samples with well characterized geometry, allows measurement of the inelastic mean-free-path. Measured values of 71 +/- 5 nm for MgO and 92 +/- 7 nm for Si for 100 keV beam energy compare favorably with calculated and experimental values from electron-energy-loss spectroscopy. Differences between the two techniques for determining t/lambda(i) and the utility of the holographic method are briefly discussed.