This electron microscope is the first environmental scanning electron microscope (ESEM) in the world. Environmental Scanning Electron Microscopy is an Australian innovation and was invented in Australia on this machine. ESEM units enable the study of objects at high magnification (up to greater than X 100,000) in their natural state or under their natural environmental conditions without destroying the object, and without an applied coating such as sputtered gold, which can destroy sensitive objects. Samples can be studied over a temperature range from -200 C to 1000 C as appropriate. There are now thousands of ESEMs in use world-wide.
The significant advancement in electron microscopy that the ESEM provided is that it can scan a sample without it having to be in a vacuum environment. A scanning electron microscope (SEM), scans a sample that is held in a high vacuum environment and coated in a conductive material, usually gold. The vacuum is required so that the scanning beam is not scattered by collisions with gas molecules. The ESEM solved this issue by using a significantly higher pressure sample chamber. The specimen chamber is isolated by valves or pressure limiting apertures and a large diameter bypass tube from the rest of the vacuum system. In addition, new detectors were invented and developed that could operate in a gaseous environment. Water vapour is commonly used as the imaging gas, and thus much less damage is caused to the sample.
ESEMs have been used to examine dynamic physicochemical properties during the swelling and dissolution of drugs and the mechanism of drug release; to study the effects of wetting and drying on wool, cotton and synthetic fibres; to follow the reaction of cement with water; to observe fresh and wet tissue such as muscle cells and connective fibres; to examine live plant seedlings, pollen, grains in situ, ants, fleas, dust mites; to investigate the degradation processes caused by environmental pollutants on paintings, sculptures and other artworks; and in investigations for soil science, polymer structure, petroleum geology, archaeology, palaeontology, ceramics, food technology, microelectronics, dentistry, microbiology, and paper coating technology.
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Damian McDonald
February 2010