Convenient multi-channel averaging for electron energy loss spectroscopy in the STEM

Electron energy loss spectroscopy (EELS) of electrons which have produced excitation of atomic electron core states promises to provide a powerful microanalytical tool. To assess fully the range of applications of the technique and its ultimate sensitivity in any given circumstance,accurate cross-sections differential in energy and scattering angle are required for both the characteristic energy loss electrons and for those loss electrons which contribute a background. In addition there is the possibility of gaining additional information on the nature of the specimen from the fine structure at the energy loss edge (Isaacson and Johnson 1975) and from the extended fine structure (EXELFS) beyond the edge (Colliex et al 1976), although neither of these phenomena are as yet well understood.We are currently investigating a number of aspects of EELS using a Vacuum Generators HB5 FEGSTEM at the Cavendish Laboratory, Cambridge. This is fitted with a magnetic spectrometer with air cored magnetic deflection at the magnet exit which can provide rapid energy scans without hysteresis.