E.P.R. and ENDOR investigation of tempone nitroxide radical in a single crystal of tetramethyl-1,3-cyclobutanedione

Abstract

Abstract The E.P.R. and ENDOR spectra of the free nitroxide radical tempone diluted in a single crystal of 2,2,4,4-tetramethylcyclobutanedione (TMCB) have been analysed and the g tensor, nitrogen hyperfine and quadrupole interaction tensors, and methyl protons tensors have been determined. It is found that the principal axes of the g tensor and of the tensors A N and Q N do not fully coincide. The negative sign of the quadrupole interaction tensor element Qzz where Z is along the direction of the nitrogen p orbital agrees with previous measurements on similar systems. This work was supported by the Centro di Studio sugli Stati Molecolari Radicalici ed Eccitati of the Italian National Research Council (C.N.R.) and in part by Ministero della Pubblica Istrusione. This work was supported by the Centro di Studio sugli Stati Molecolari Radicalici ed Eccitati of the Italian National Research Council (C.N.R.) and in part by Ministero della Pubblica Istrusione. Notes This work was supported by the Centro di Studio sugli Stati Molecolari Radicalici ed Eccitati of the Italian National Research Council (C.N.R.) and in part by Ministero della Pubblica Istrusione.