Design and construction of magnetic resonance spectrometer with applications to the study of irradiated organic single crystals

In this dissertation, the interfacing of a K-band spectrometer with a closed cycle helium refrigerator is discussed. This system was found to present many advantages over previously employed cold flow systems. In particular, the system allowed continuous cooling of samples to approximately 10 K. To determine the operational parameters and abilities of the system, a molecule which had been studied previously by the same K-band spectrometer, 6 methylmercaptopurine riboside was studied. The primary study presented in this dissertation involved the molecule N-phenyl N-benzo hydroxamic acid (PBHXA). When this molecule is exposed to ionizing radiation, radicals are formed in close enough proximity that radical-radical dipolar couplings can be observed. These couplings, in combination with the observed g factor variations, enabled a preliminary crystal structure to be obtained. In addition, it was found that the monoradical structure corresponded to a nitroxide radical. Finally, an extensive library of computer programs for data acquisition, experimental control, and analysis were developed. Two of these programs, one for data acquisition of ESR signals, the other for data acquisition of signal averaged ENDOR, are presented in this dissertation. All programs are available from the author upon request