Dark-Field Contrast of Elements in High-Voltage Electron Microscopy

Abstract
A new and simple expression developed by us has been used for the estimation of contrast of thin amorphous specimens in the tilted-beam mode of dark field (DF) imaging using a conventional transmission electron microscope (CTEM). DF contrasts calculated for thin amorphous films of some representative elements in the electron accelerating voltage range between 0.1 to 3.0 MV have been compared with the corresponding bright field (BF) contrasts. The magnitude of the gain in contrast in the DF mode compared with BF one, observed over a wide range of accelerating voltage (φ), microscope aperture (α) and atomic number (Z) of elements, has been highlighted.