Single crystals of l-asparagine monohydrate and partially deuterated l-asparagine were x-irradiated at 4.2K, 77K, and room temperature by a 3Mev Van de Graaff electron accelerator. Several free radical species were produced by the x-irradiation and were studied by X-band ESR and ENDOR from 4.2K to 300K. X-irradiation at 77K produced two anion radicals, radicals I and III, with the unpaired spin at the carboxyl, and amide end of the molecule, respectively. Production of III must be less probable than I, since the ESR spectra of III appear to be less intense. X-irradiation at 77K also produced one cation radical (II), the decarboxylation radical. The ESR spectra of radical I are the most intense. Hyperfine tensors were determined for hydrogen ENDOR lines belonging to radicals I, II, and III. In addition, ENDOR lines for one nitrogen and two deuterium lines were observed. Tensors were determined for the nitrogen and one of the deuterium nuclei. These nitrogen and deuterium couplings were needed to explain the ESR spectra of radical II. There was probably another radical present at 77K, but there was not enough information to identify it. Radicals I, II, and III were also produced by x-irradiation at 4.2K. New unidentified ENDOR lines appeared after warming to 128K. Radicals I, II, and III were still observed at this temperature, but the ESR spectra have changed somewhat. After warming to 150K, radical I's ESR spectrum was not observed. Radical VI, the deamination radical, appears to begin to grow in at this temperature. Upon warming to 210K, radical II began decay by hydrogen abstraction to form radical IV which was identified in an earlier room temperature study. Three new ENDOR lines, though not completely followed through all orientations, combine correctly to predict the ESR spectral width along the c axis. Radical VI's ESR spectra became stronger after / warming to room temperature. For x-irradiation (of deuterated samples) at 300K, radical VI's spectra was much weaker than radical IV's, but for x-irradiation at 77K followed by warming to 300K radical VI's spectra was almost as intense as radical IV's spectra. / Source: Dissertation Abstracts International, Volume: 46-09, Section: B, page: 3105. / Thesis (Ph.D.)--The Florida State University, 1985.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_75660 |
| Contributors | COLEMAN, JOHN MELTON., Florida State University |
| Source Sets | Florida State University |
| Detected Language | English |
| Type | Text |
| Format | 209 p. |
| Rights | On campus use only. |
| Relation | Dissertation Abstracts International |
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