Image potential in scanning transmission electron microscopy

In the framework of the classical dielectric theory, the role of the image potential in electron energy loss spectroscopy (EELS) of fast electrons com monly used in scanning transmission electron microscopy travelling near a s urface is studied. Relativistic and dispersive corrections are evaluated to establish the range of validity of this theory. The spatial resolution of the EELS technique is discussed for valence and core electron excitations. The effect of the quantal nature of the probe is also discussed. Finally, s everal problems involving planar surfaces, small particles, cylinders and t runcated targets of interest in nanotechnology are studied. (C) 2000 Elsevi er Science Ltd. All rights reserved.