The Scanning Electron Microscope (SEM)
Scanning electron microscopes are used for imaging small specimens at magnifications from 100 to 100,000 times their actual size. They do this by collecting emitted electrons, rather than collecting light like traditional optical microscopes. The images produced are unique for their extreme and realistic depth of focus – for example, for maintaining the perspective the human eye is accustomed to for making insects life-like. The instruments permit scientists and engineers to view tiny objects or features very closely, thereby allowing biologists to see an organism's protective coating, or metallurgists to inspect corrosion of metals, or geologists to quantify mineral abundances, study mineral assemblages as well as quantify mineral associations.
The SEMs here within Memorial University's Bruneau Centre include a FEI Quanta 400 for serving general applications in mineralogy, biology, physics and chemistry, and a FEI MLA 650F for serving applications that demand higher resolution. Both SEMs are also capable of environmental SEM (ESEM), which refers to these SEMs' capability for working at variable pressures or near atmospheric pressures instead of limited to high vacuum. ESEM also allows for almost any specimen to be examined, including wet and non-conducting specimens.
For accommodating the variety of information available from electron interaction, our SEMs are also equipped with high throughput energy dispersive x-ray (EDX) analytical systems from Bruker, an electron backscatter diffraction (EBSD) system from HKL, and cathode-luminescence (CL). Both SEMs are also capable of x-ray aided image analysis, i.e., Mineral Liberation Analysis® or MLA®. The MLA software automates image acquisition, stage movement and x-ray acquisition for spatially quantifying mineral abundances and associations of areas as large as a typical section of rock in less than 2 hours.