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Electron paramagnetic resonance spectra from gamma-irradiated potassium thiocyanate

1969; Elsevier BV; Volume: 30; Issue: 7 Linguagem: Inglês

10.1016/0022-3697(69)90243-1

1879-2553

R. Kewley,

Photochemistry and Electron Transfer Studies

The electron paramagnetic resonance spectra of two distinct radical species have been observed following the gamma-irradiation of potassium thiocyanate single crystals. The spectrum of the first species appears when a crystal is irradiated at 77°K. For this radical there are two magnetic sites, each characterized by principal g values g∥ = 2.004 and g⊥ = 2.025 and by principal values of the hyperfine coupling tensorA∥ = 8.9 and A⊥ = 1.4 Mcs. For the two sites the radical axis makes angles of 22° and 158° with the (010) axis and in each case the radical axis lies in the (100) plane of the crystal. The five line hyperfine pattern shows that this radical contains two equivalent N14 nuclei and it is identified as the V-center (NCS)2−. The spectrum of the second radical is observed in the temperature range 103°-181°K. This species is also situated at two magnetic sites and has principal g values 2.034, 2.018 and 2.014. It exhibits a three line hyperfine pattern from one N14 nucleus, the principal values of the hyperfine coupling tensor being 5.6, 6.6 and 6.4 Mcs. The nature of this second radical is discussed.