ELECTRON ENERGY-LOSS SPECTROSCOPY OF HIGH-ANGLE THERMAL-DIFFUSE-SCATTERED ELECTRONS IN TEM

New techniques are introduced to acquire the electron energy-loss spectra (EELS) of high-angle thermal-diffuse-scattered (TDS) electrons in a conventional transmission electron microscope (TEM). TDS-EELS is shown to be temperature sensitive and may contain information about atomic Debye-Waller factors. Significant differences have been observed in TDS-EELS in comparison to the EELS acquired in the bright-field mode. Experimental conditions have been investigated to optimize signal intensities. TDS-EELS spectra of a Si crystal have been used to deduce the atomic mean vibration amplitude of Si atoms. It has been shown that multiple plasmon scattering has little effect on data acquisition and that the signals are generated primarily by phonon-single electron, double-inelastic scattering processes. However, it has not been confirmed which of the coherent and incoherent double scattering processes is the dominant mechanism, because the experimental data appear not to support the incoherent model.