TEACHING INSTRUMENTAL TECHNIQUES: ELECTRON MICROBEAM METHODS FOR THE EARTH AND MATERIALS SCIENCES

Electron microbeam methods (SEM, EPMA) are taught in our facility as a single-semester course to students from a wide variety of disciplines (geology, anthropology, engineering, chemistry, physics) that deal with non-biologic materials. Recognizing their varied scientific interests and that their future research may involve the use of analytical platforms different from that in our facility, instruction stresses four principle areas: theory, application, relevance, and alternatives. Operational theory is presented by classroom lecture. Without hands-on experience, however, operational theory remains an abstract concept. Therefore, lecture is augmented with weekly 1-2 hr individual lab sessions (on our EPMA) that are designed to demonstrate the theories presented. A by-product of these exercises is familiarity with the operational firmware and software of our system, but this is not considered the fundamental (i.e., testable) goal. This portion of the course is designed to occupy roughly half the semester, and is broken into two main segments: imaging and image analysis, and x-ray analysis. At conclusion, the lecture presents a synopsis of alternative microanalytical techniques to address materials problems that are beyond the limits of resolution and detection by SEM/EPMA. Just as theory remains abstract without application, so does application tend to remain abstract without relevance. Hence, the second half of the course is occupied by a research project directed at samples of the student's choice. The project requires characterization utilizing simple imaging, digital image analysis, and compositional analysis, thus reinforcing the concepts taught in a practical manner. The project report is not directed at solving the student's research problem, but rather is focused on documenting analytical methods and careful analysis of the quality and statistical significance of the data obtained. This leads the student through the logical steps involved in acquiring and assessing data, and serves as a guide for future research. Although limiting course enrollments to about 6 per semester, these methods are intended to provide students with a background that will permit them to efficiently acclimate to other electron beam platforms, and to evaluate data reported in literature.