On Tuesday, December 6, 2022, at 7:00 p.m., we’ll be having our monthly meeting live and in person, featuring…
Introduction to Vibrational Spectroscopy for Mineral Identification
with Dr. Arthur McClelland
This month’s speaker has been invited back for a return engagement. After his last talk in 2016, our own George Adelman took an interest in Raman spectroscopy, which spurred him to learn the technique and purchase his own equipment, which has morphed into our regular mineral ID service for the club. The ability to analyze tiny samples of minerals is a major breakthrough for our hobby, allowing us to turn many of those pesky “unknowns” into treasured “knowns.”
Dr. McClelland received his PhD in applied physics from the University of Michigan in 2009. He has been a staff scientist at the Center for Nanoscale Systems at Harvard University since 2011, focusing on materials characterization techniques. He is the son of a retired geologist and grew up collecting fossils in West Virginia.
In his talk, Dr. McClelland will present in simple terms the fundamentals behind two techniques for using the vibrational properties of light as it interacts with chemical bonds to reveal the composition of mineral grains. Fourier transform infrared (FTIR) spectroscopy and Raman spectroscopy are two established methods he uses in his lab at Harvard. Vibrational spectroscopy uses light to measure the vibrational frequency of the chemical bonds in a material. Each mineral will have a unique set of vibrational frequencies due to its unique chemical and crystallographic properties. The unique sets of vibrational frequency spectra are tabulated in digital libraries, such as the free RRUFF database online, which allow an analyzed spectrum to be compared with thousands of known standards. Dr. McClelland assures us that no previous knowledge of spectroscopy is assumed, and the talk should be accessible to all.