Radiation-Induced Free Radicals in Sulfur Compounds. ESR Studies in the Polycrystalline State
Secondary processes occurning in organic sulfur compounds, irradiated wtth ionizing radiatton in the dry state, were followed by ESR spectroscopy. Samples were irradiated in vacuum at 77 deg K and the ESR spectra recorded at this temperature before and after stepwise heat treatment at successively increasing temperatares. The resonance spectra seem to indicate that after irradiation at 77 deg K, several kinds of ESR centers are formed. No or very few sulfur radicals seem to be formed at this temperature. The results show that few secondary processes proceed efficientiy in solids in the temperature range from 77 to about 110 deg K. Depending upon the compound, decay processes seem to dominate in the temperature range varying from about 110 deg K and up to about 250 deg K. Upon further heat treatmert, secondary reactions take place which lead to the formation of sulfur radicals. The threshold temperature for the reactions was about 170 deg K for simple thiols and disulfides, 240 deg K for peptides like glutathione, and about 280 deg K for proteins. The formation of sulfur radicals was found to coincide with an increase in the total number of observable ESR centers. Thus, in the case of penicillamine, the number of unpaired spins observed after annealing to 295 deg K exceeded the initial value at 77 deg K by about 70%. Evidence is presented that diffusion-cortrolled intermolecular reactions take place in irradiated solids, and it is suggested that the observed formation of suifur radicals may in part be explained by such a mechanism. The resonance pattern due to polyoriented radicals of the type R-- CH/sub 2/-- S. (cysteine, cysteamine, giutathione, proteins) was found to exhibit a temperature dependent hyperfine splitting which is not found for radicals of the type R-- CX/ sub 2/-- S. (penicillamine).
- Research Organization:
- Norsk Hydro's Inst. for Cancer Research, Oslo
- Sponsoring Organization:
- USDOE
- NSA Number:
- NSA-17-008165
- OSTI ID:
- 4734571
- Journal Information:
- Journal of Chemical Physics, Journal Name: Journal of Chemical Physics Journal Issue: 10 Vol. 37; ISSN JCPSA6; ISSN 0021-9606
- Publisher:
- American Institute of Physics (AIP)
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
Similar Records
TRANSFER OF RADIATION-INDUCED UNPAIRED SPINS FROM PROTEINS TO SULFUR COMPOUNDS
ELECTRON-SPIN RESONANCE STUDIES OF BOVINE-SERUM ALBUMIN AND CYSTINE IRRADIATED WITH $gamma$-RAYS AT 77 K AND AT ROOM TEMPERATURE