The electron microscope laboratory currently houses a Hitachi S-3500N variable pressure Scanning Electron Microscope (SEM) with a resolution of 3 nm. It can examine non-conductive hydrated biological samples at a maximum pressure of 240 Pa. using a Robinson Backscattered detector in variable pressure mode. The Robinson detector is also used to examine samples using high energy backscattered electrons that emphasize atomic number differences in the sample.The SEM is also equipped with an EDAX x-ray microanalysis system (energy dispersive spectroscopy) with a liquid nitrogen free 10 mm2 silicon drift detector that can detect elements down to boron (131ev resolution). This technique is non-destructive to the sample and sensitive to elements in concentrations as low as ~1000 ppm. The system also allows the collection of x-ray area maps where each element in a non-homogeneous sample can be assigned a different color thus revealing not only the presence of a particular element but its location and abundance on the sample surface.
Research in the electron microscope laboratory encompasses a wide variety of disciplines including biology, chemistry and geology. Projects have involved the ultrastructure of bleached foraminifera in response to ultraviolet rays in sunlight, the discovery and imaging of marine viruses in copepods, high resolution TEM of marine viruses and the sizing and chemical classification of African and Saharan dust particles. The SEM has been pivotal in the imaging of benthic foraminifera for taxonomic purposes so that individual species can be correctly classified using shell morphology as one criteria. The laboratory also works closely with the United States Geological Survey in assisting them with various research projects such as the response of benthic foraminifera to increasing pH levels in the ocean (ocean acidification). Benthic foraminifera such as Amphistegina gibbossa serve as bioindicators of coral reef health.
Two graduate level courses are offered in alternating semesters on the theory and techniques of Transmission Electron Microscopy and a separate course on the theory and techniques of Scanning Electron Microscopy. Students are given hands on training in specimen preparation and instrument operation as well as background theory in classroom lectures. A personal project in each class assures that students have mastered the basic fundamentals of TEM and SEM.
The TEM, SEM and x-ray microanalysis instruments as well as the specimen preparation equipment are available to researchers outside the College of Marine Science, USF.
Currently the cost of using the laboratory is $90.00/hour for those outside the USF system.
Tony Greco, USF College of Marine Science, 140 7th Ave. South, St. Petersburg, Fl 33701
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