title: Mobility and free radical concentration effects in proton-electron double-resonance imaging.
abstract: The dependence of the enhancement of proton-electron double-resonance images upon the mobility of the proton bearing molecules, of the concentration of free radicals, and of the pulsed saturating RF power is studied in a magnetic field of 16 mT. The data exhibit a behavior which, in the potentially interesting region of small free radical concentration, may differ substantially from the high-concentration regime depending upon experimental conditions. The results permit a clearer understanding of the factors determining enhancement and contrast in images obtained by dynamic nuclear polarization.
authors.affiliation: Departamento de Física, Universidade Federal de Pernambuco, Recife, Pernambuco, Brazil.
authors.forename: P L
authors.initials: PL
authors.lastname: de Sousa
authors.forename: R E
authors.initials: RE
authors.lastname: de Souza
authors.forename: M
authors.initials: M
authors.lastname: Engelsberg
authors.forename: L A
authors.initials: LA
authors.lastname: Colnago
mesh_terms: D004578:Electron Spin Resonance Spectroscopy; D005609:Free Radicals / Q000032:analysis; D005990:Glycerol / Q000737:chemistry*; D007089:Image Enhancement; D007474:Ion Exchange; D008279:Magnetic Resonance Imaging; D008280:Magnetics; D008961:Models, Structural; D011522:Protons; D014783:Viscosity
chemical_list: D005609:Free Radicals; D011522:Protons; D005990:Glycerol