Cory D. Jaques
Honors in Chemistry:
Electron Nuclear Double Resonance Spectroscopy of Radicals
Electron Nuclear Double Resonance (ENDOR) spectroscopy is a spectroscopic technique that detects a Nuclear Magnetic Resonance signal via the intensity change of a simultaneously excited Electron Paramagnetic Resonance line. It can provide valuable information about a system that is not available through any other spectroscopic method, such as the identity of the components of a system and the structure of a molecule. The purpose of this project was to make it possible for any student to be able to measure ENDOR spectra as needed. The Hampden-Sydney College Chemistry Department first acquired a grant from the National Science Foundation in 1984 for the purchase of equipment to construct an ENDOR spectrometer. Since then, students at Hampden-Sydney have made various attempts to assemble a working ENDOR spectrometer, including modifying a prototype ENDOR cavity which was acquired by Dr. Sipe during a sabbatical at the University of Alabama. Though never fully successful, their work was consulted frequently and was invaluable to the ultimate success of this project. In 2002 the department received support from the Spalding Professorship held by Dr. Sipe to purchase an ENDOR cavity. With this cavity installed, the other components of the ENDOR spectrometer were added to the existing EPR spectrometer, and its sensitivity and performance were verified and monitored over time. ENDOR spectra were measured for the tri-tert-butylphenoxyl radical and were shown to be consistent with the literature references. A detailed procedure is given for future students to reproduce this experiment, and to be able to conduct other ENDOR experiments for known and unknown samples.