BiHall Microscope Valuable to All

Last year, the College’s geology department unveiled a new Scanning Electron Microscope (SEM), a high performance machine capable of advanced imaging and analysis at very fine levels. The machine boasts an impressive array of features that include three-dimensional imaging as well as the chemical analysis of a sample down to the element. It is available to all departments of the school, and to researchers from around Vermont, yet rarely does anyone outside of the geology department use it.

The magnifying power of traditional light microscopes, just like the ones you used in high school biology, pales in comparison to the SEM. Compound light microscopes are only capable of magnifying a sample to 1,000 times its normal size, and the image appears flat. The SEM at the College, on the other hand, has a maximum magnification of well
over 100,000.

Not only is the power of magnification significantly greater, but the resolution of the SEM is unparalleled, unmatched by compound light microscopes. Even at equivalent magnifications, images generated by the SEM are in far greater detail and allow researchers to examine fine microstructures that otherwise would never be discernible.

How, then, does a SEM work, and why is it capable of much greater magnification and resolution than a traditional light microscope? In a SEM, rather than using light, a high-energy beam of electrons is directed through a series of electromagnetic fields and lenses and focused onto the sample, such as a sliver of rock or a small marine shrimp. The use of electrons, which have a much shorter wavelength than light in the visible spectrum, gets around some of the limitations that traditional microscopes have in resolving an image. The beam excites the sample, causing it to emit signals such as electrons and X-rays.

Detectors use these emitted signals to relay the information to a computer, which constructs an image. The beam allows for a continuous scan of the sample capable of detecting minute topographical features, and the emission of characteristic X-rays allows for elemental analysis. The end result is somewhat otherworldly: sleek images peppered with details that look almost too realistic.

The geology department already makes good use of the SEM. Geology students often use the microscope to determine the chemical composition of rock samples. The SEM can detect individual elements and generate colored images illustrating how they are layered in the formation of the rock. This chemical detection can be used in all sorts of studies, such as those dealing with the origins of groundwater contamination or those looking at how certain types of rocks form.

In biology, the imaging capabilities allow for analysis of morphological features that can be used to identify tiny creatures, from insects to bacteria. SEMs are also used quite frequently in forensics, as well as in nanotechnology industries.

But the applications go beyond the sciences, and Professor of Geology David West wants to encourage non-science majors to find ways of incorporating the SEM into their work. Any work that deals with small material or with chemical composition can benefit from a SEM. Art history majors, for instance, can use the chemical analysis capabilities to identify the origins of paintings by looking at the composition of the dyes and paints. Artists themselves, especially photographers, can explore a whole new world of creativity – even on a microscopic level, there are beautiful still-life arrangements (look up some examples by searching ‘snowflake crystal SEM’).

But most students have not yet taken advantage of the SEM. Though several different classes incorporate the SEM into their curriculum, only one non-geology course makes use of it: students of Invertebrate Biology look at the fine hair-like structures on scorpion legs. Only geology students use the SEM for independent work, as their senior theses require them to do so. Given the small slice of the student body that actually uses the SEM, it is frequently available for use.

It appears that the only students that use the SEM are the ones who are told about and who are required use it. It was never the intention of the geology department to make it an exclusive and mysterious resource. In their grant application, the College emphasized that they wanted to make it available to students of all disciplines, including non-science majors, as well as for aid in any research in the state of Vermont.

The SEM is a hidden gem of BiHall. It is an incredible machine that is underused. It may take some creativity to figure out how to work something like this into some independent projects, but for many disciplines it is a resource that can easily open up new doors.

It is not difficult to set up an appointment – just contact David West or Jody Smith, the resident experts on SEM use.