Lorentzian-Iske image blur of gold nanoparticles on thick amorphous silicon films in ultra-high-voltage transmission electron microscopy

摘要

Abstract We quantitatively analyzed the contrast degradation and blur of 20-nm gold nanoparticles adsorbed on the top of amorphous silicon films of thicknesses of 0.54, 1.09, 1.63 and 2.2 |im in bright-field transmission electron microscope (TEM) images taken at accelerating voltages of 0.5, 1, 2 and 3 MeV. The thickness dependence of the transmission was well explained and consistent with our calculations. The blur function, derived by assuming that the TEM image of a thick specimen can be reproduced by convolving the TEM image of a very thin specimen with it, was found to be expressed by a two-dimensional Lorentzian function. Considering the two characteristics of the Lorentzian function, a sharp peak around the center and a long tail, we concluded that, for TEM observations of thick specimens, the image contrast is degraded predominantly by inelastic scattering and the image is blurred predominantly by multiple elastic scattering.