ENDOR spectra of nitroxide radicals in disordered matrices

Abstract
An ENDOR study on several nitroxide radicals included in polycrystalline and glassy matrices is reported. A calculation program has been developed to simulate ENDOR spectra of radicals in disordered matrices. The shape of the computed spectra can be changed from crystal-like to powder-like type through the intermediate cases. The principal values of the AH hyperfine tensors have been obtained for tempone, tempol, tempyo and di-t-butyl-nitroxide. The influence of the host matrix on radical conformations is also discussed.