USING TRANSMISSION ELECTRON MICROSCOPY (TEM) IN GEOSCIENCES EDUCATION AT THE UNDERGRADUATE AND GRADUATE LEVELS

The transmission electron microscope (TEM) has long been recognized as a powerful research tool in the geosciences. No other instrument is capable of the broad range of analyses at micro-and nano-scales that TEMs afford (e.g. high resolution imaging, diffraction, discrete chemical analyses). Because of this versatility, the TEM has the potential to be a powerful teaching tool, as well. However, due to the high purchase prices, costly usage time, and difficulty of operation, the TEM is often not used as such. In the cases of X-ray diffraction (XRD) or scanning electron microscopy (SEM), while the intricate theoretical details may pose a challenge for some undergraduate students, instrument operation is often tractable within one or two training sessions. The nature of the TEM requires that students have a solid grasp of both the abstract concepts of electron interactions with fields and matter, as well as the concrete operation of the instrument, which is often recalcitrant. However, our experiences show that teaching undergraduates using TEM as both an instructional and research tool positively affects students’ understanding of, and interest in, basic geosciences concepts and prepares them for a graduate career where TEM is a major part of their own research.

The level of instruction must necessarily vary based on the level of the student. At the beginning of a student’s geosciences career, the TEM can best be used in demonstrative learning – by displaying in short lab sessions high resolution imaging or electron diffraction. The goal at that level is to produce interest in the technique and geosciences in general. At the mid-undergraduate level, the students often do some basic TEM operations themselves and might be expected to help in the analysis of data collected by a professor or graduate student. The goal at that level is to start giving the student more autonomy in data collection and data analysis. As the students progress through their career, the ultimate goal is that they will be effective in the use of the TEM for their own senior thesis research projects and will want to pursue more TEM work in their graduate career. Although time and cost intensive, this mode of instruction builds students with a competitive background that may serve as a catalyst for long term future success.