A technique is proposed for reducing unwanted diffraction contrast
when imaging second phases in crystalline materials using transmission
electron microscopy. With the suggested name of plasmon-ratio imaging,
the technique uses an energy-filtered imaging system to record and
determine a ratio for two images taken at energies in the low loss
region. Unlike core-loss imaging, the use of very thin specimens is not
required. It is concluded that it is often possible to create a ratio
image in which the contrast is dominated by energy loss, that is,
chemical differences, rather than by diffraction effects.