Analyses of the electronhyphen;spinhyphen;resonance (ESR) hyperfine powder spectra of nitroxide radicals enriched with15N (I=1/2)

摘要

A detailed investigation has been performed to analyze the electronhyphen;spinhyphen;resonance (ESR) properties of a nitroxide radical (TANOL) isotopically enriched with15N with a nuclear spinI=1/2 in amorphous samples of a polycarbonate polymer. Unlike the case of14N withI=1, the15N ESR hyperfine powder spectra consist of two components that are well resolved at anXhyphen;band microwave frequency and each hyperfine component displays resolved powderhyphen;pattern structures so that the values of all the principal Zeeman and hyperfine coupling constants can be unambiguously determined asgx= 2.0096,gy= 2.0062,gz=2.0022,Ax/(gxthinsp;mgr;B)=minus;1.00 mT,Ay/(gythinsp;mgr;B) =minus;1.00 mT,Az/(gzthinsp;mgr;B) =minus;4.89 mT, with an accuracy of plusmn;0.0004 for thegivalues and plusmn;0.0015 mT for theAi/(githinsp;mgr;B) values.