Electron Spin Resonance in the Study of Radiation Damage 



251 



peak corresponding to the g^^ value. Such a resonance will have a shoulder or 

 shelf on one side with the edge of the shoulder corresponding to ^i,. First 

 derivatives of an asymmetric resonance arising from an anisotropic g factor 

 in x-irradiated cystine are shown in Fig. 4 for three different observation 

 frequencies. That the apparent structure in these curves is due to anisotropy 



NO OF RELATIVE 

 HYDROGENS COUPLING 



EXPECTED PATTERN OF RESONANCE 



Fig. 3. Some illustrative theoretical hyperfine patterns of radicals with two sets 



of H nuclei (or other nuclei of spin |). All nuclei of one set have the same 



coupling, but those of the two sets dilTer as indicated. 



in the g factor has been established by measurements on a single crystal of 

 cystine at different orientations in the field (19). Such curves show some 

 differences depending upon amount of modulation, variations in natural line 

 widths, degree of anisotropy in g, as well as variations in observation frequency 

 or H value. Nevertheless, there should always be a bend point in the derivative 

 curves corresponding to the H for resonance at ^^j^ and a lesser one for _^||. 

 This fortunate circumstance allows measurement of ^^^[ and gj_ even in poly- 

 crystalline samples. The identity of these bend points, if in doubt, can usually 



