High-frequency time domain electron paramagnetic resonance : methods and applications

There are numerous advantages to high frequency (high field) electron paramagnetic resonance (EPR) spectroscopy. Two of the most important are improved sensitivity and the improved resolution of field dependent interactions. In addition, there are many attractive features to time domain spectroscopy. Pulsed EPR allows for the design of experiments, which can specifically be used to study structure and dynamics of paramagnetic species and provide utmost resolution by separating interactions from each other. The combination of pulsed techniques and high frequencies is not only complimentary to continuous wave (CW) low frequency EPR but it also greatly increases the accessible information on paramagnetic species. High frequency, time domain EPR is still in its infancy. Spectrometers at W-band ([approximately] 95 GHz) are now available commercially but to date very few spectrometers operating at higher frequencies have been described. The spectrometer developed in the Francis Bitter Magnet Laboratory operates at a microwave (MW) frequency of 139.5 GHz corresponding to [approximately] 5 T magnetic field. The applications presented in this thesis illustrate the potential of high frequency, time domain EPR spectroscopy at 139.5 GHz in obtaining structural and mechanistic insights of several paramagnetic systems. Well resolved EPR spectra observed at 139.5 GHz of the stable tyrosine radical in ribonucleotide reductase (RNR) revealed the existence of a hydrogen bond in RNR from yeast, chapter 1. The bond length and orientation were determined from the nuclear frequencies of the proton, detected by orientation selective electron nuclear double resonance (ENDOR).

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Chemistry.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2004

Author dc:creator

• Bar, Galit, 1970-

Advisor dc:contributor.advisor

• Robert G. Griffin.

• Chemistry.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/17826

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/17826