Electron spin: echo studies of nitroxide free radicals in liquids
- Univ. of Illinois, Chicago
Direct measurements of the electron transverse (T/sub 2/) and longitudinal (T/sub 1/) relaxation times of two nitroxide free radicals in liquid solution have been carried out over a range of concentrations and temperature by the method of electron spin-echoes (ESE). Reorientational correlation times and the Heisenberg exchange rate for these radicals in toluene were obtained from the ESE data and compared with results from continuous wave (CW) EPR experiments. The radicals studied were perdeuterated Tempone (PDT) which is roughly spherical in shape and deuterated (in the nitroxide moiety) N-(p-methoxyybenzylidene)-4-amino-2,2,6,6-tetramethylpiperidinyl-1-oxy (DMBATPO) which is rod shaped. The Heisenberg exchange rates are approximately equal for the two radicals in toluene whereas the correlation times as well as the anisotropy of rotational diffusion are quite different for the two spin probes. The inhomogeneous broadening of nitroxide line shapes from unresolved intramolecular proton or deutron hyperfine interactions must be considered when extracting relaxation data from CW spectra whereas the ESE measurements are independent of any source of inhomogeneous broadening. The electron spin-lattice relaxation rates for these two radicals in toluene and the liquid crystal n-(p-methoxybenzylidene)-p-butylaniline (MBBA) were measured and are far less sensitive to the motion of the radicals than is the electron spin-spin relaxation rate.
- OSTI ID:
- 5490208
- Journal Information:
- J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 83:26; ISSN JPCHA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
400302 -- Organic Chemistry-- Isotope Effects-- (-1987)
400600* -- Radiation Chemistry
ACOUSTIC ESR
AROMATICS
DATA
DATA FORMS
DEUTERIUM
ELECTRON SPIN RESONANCE
ELECTRON TRANSFER
EXPERIMENTAL DATA
HYDROGEN ISOTOPES
INFORMATION
ISOLATED VALUES
ISOTOPE EFFECTS
ISOTOPES
LIGHT NUCLEI
MAGNETIC RESONANCE
NUCLEI
NUMERICAL DATA
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
RADICALS
RELAXATION
RESONANCE
STABLE ISOTOPES