The grant supports acquisition of components to upgrade an existing micro-Raman spectroscopy system in the Department of Geosciences at Princeton University. The Raman spectrometer is primarily used by the high pressure research group at Princeton for rapid non-destructive mineralogical analysis of standards for pressure determination (e.g., ruby fluorescence) and is an essential component for high-pressure diamond anvil cell experiments to study the properties of deep Earth mineral phases. Funding will support acquisition of a new laser, CCD detector, and spectrometer. The upgraded Raman system will support faculty and student research beyond Geosciences at Princeton and student training will be facilitated through hands on experiential learning as part of analytical coursework.
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Raman spectroscopy is a tool of growing importance for study of geological materials. It is a rapid, non-destructive, and simple method to obtain constraints on a range of properties including, mineralogy, structure, composition, purity, strain, degree of disorder, and nature of inclusions on all types of materials. The Raman effect is an inelastic light scattering process in which laser light is used to excite a sample to a higher electronic state. The sattered light is then collected and recorded. This resultant signal contains a shift in energy from the laser frequency corresponding to differences in energy levels of the sample. Different vibrational modes of structural units within a sample will produce a set of recognizable Raman peaks in the measured spectrum. The Raman techniuqe is also an important component many types of high-pressure experiments as it is essential for preparation of diamond anvil cell (DAC) experiments, pressure measurement, and characterization of sample materials before and after compression. High-pressure Raman scattering experiments provide important constraints on bonding, phase transitions, and crystal structure. In this project, we obtained and installed a new Raman spectrometer (LabRam HR Evolution, Horiba) (see Figure) that provides significantly enhanced capabilities both for high-pressure research and for a wider range of geological applications. In the short period of time we have had the system so far it has been used by graduate and undergraduate students for a number of projects including studies of compression-induced structural changes in silicate and sillenite minerals and for characterization of a gem collection. These applications will expand in the future, and we will also incorporate Raman spectroscopy in undergraduate research and teaching.
