A CM300 FEI electron microscope (right) operates in RSES as part of the ANU's Electron Microscope Unit. The instrument, installed in 1999, uses 300 kilovolt electrons to produce high magnification images and diffraction patterns of thin (<1µm) specimens. For RSES purposes, these specimens are mostly rocks and minerals, but this facility is used university-wide by research staff and students to characterise materials ranging from ion-implanated semiconductors to BN nanotubes to sea urchins.
The 300 kV incident electron beam has a high penetrating power for thin specimens, but also a characteristic wavelength 0.00197nm which leads to strong diffraction from regions down to several nanometres across. This diffraction, together with energy-dispersive analysis of fluoresced X-rays for chemical information, leads to very powerful capacity for characterisation of nanometre-sized features.
Coupled with an imaging resolution of 0.2nm, a capacity to tilt specimens up to 60° provides unparalleled opportunity for nano-characterisation. For example, the micrograph above shows an interface between amphibole (top right of image) and pyroxene (bottom left of image) with strained ledges 1-3nm in height which probably enhanced metamorphic fluid access to this crystal interior in the Musgrave Ranges of Central Australia. The lines of dots represent clusters of atoms directly imaged as crystal lattices.Even when not operated at highest magnification, the TEM provides a range of information about microstructures at the submicron level that is difficult to obtain any other way. For general electron microscopy information, go towww.anu.edu.au/EMU/index.htm