Secondary electron energy loss coincidence (e,2e) spectroscopy on Ag and Si surfaces

Abstract

Qualitative information on the mechanism of secondary electron emission with respect to loss processes has been gathered by measuring the coincidences between secondary electrons and inelastically backscattered electrons on a polycrystalline silver (Ag) and an amorphised silicon (Si) sample using a specially designed (e,2e) coincidence spectrometer. Primary electrons impinge on the sample with an energy of 100 eV. Correlated emission of electron pairs was observed with a hemispherical mirror analyzer (backscattered electrons with losses up to 50 eV) and a time of flight analyzer (secondary electrons with energies up to 50eV). A comparison of these experimental data with a Monte Carlo (MC) simulation model is made. It is found that surface excitations play an important role in secondary electron emission mechanism. For Ag, low energy loss distributions were compared with calculations using linear response theory and agreed satisfactorily even though the expected limit of validity of this type of theories is for energies ≥100 eV.