ORIENTATION DEPENDENCE OF MEASURED INELASTIC-SCATTERING PROBABILITIES FOR FAST ELECTRONS IN SINGLE-CRYSTALS

When a well-collimated beam of high-energy electrons traverses a thin single-crystal specimen (as in transmission electron microscopy), an inelastic event may induce an angular spread in the inelastic beam, effectively reducing collimation. Calculation of the 'smeared out' diffraction contrast preserved in the inelastic beam indicates that measured mean free paths for discrete excitations may alter with diffraction conditions. Theory is correlated with experimental observations for plasmon and nitrogen K-loss signals from single-crystal aluminium nitride platelets. These results enable favourable diffraction conditions for quantitative microanalysis of single crystals by electron energy-loss spectrometry to be defined.