Free radical motion in super critical fluids probed by EPR spectroscopy

Article Abstract:

Electron paramagnetic resonance spectroscopic studies were performed to describe free radical reactions in the 2,2,6,6-tetramethyl-1-piperidinyloxy radical in super critical fluids (SCF). In addition, liquid ethanol, n-hexane and other nitroxide samples were also examined. The spin rotation and Heisenberg spin-exchanges of the free radical samples were measured. The findings revealed that solvent density regulates the spin rotation and spin exchange rates among nitroxides in SCFs. Moreover, free radical motion may be determined if the SCF density is lower than the critical density.

Free radicals (Chemistry), Free radicals, Free radical reactions

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Spin exchange of cation radicals in solid polymeric matrixes

Article Abstract:

Research was conducted to examine the spin exchange of cation radicals in solid polymeric matrixes. Electron paramagnetic resonance spectroscopy was used to determine the rate of spin exchange between cation radicals held in rigid polymeric matrixes. Various diamagnetic compounds were added to the samples to investigate the idea of "superexchange" which was proposed in earlier work. Results indicate that the mechanism is incorrect and that the measurement of exchange energies can be employed to find relative separations of radicals held in the polymeric matrixes.

Polymers, Cations, Radicals (Chemistry), Nuclear spin

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High dielectric hyperbalanced polyaniline materials

Article Abstract:

The effect of the microcrystalline size dependence of different polyaniline polymeric systems on the dielectric constant is examined. The mechanism of the increased dielectric response at higher frequencies is investigated by EPR spectroscopy and the results have shown that delocalized polarons might provide a way to boost the dielectric response at high frequency.

Dielectrics, Dielectric materials, Mechanical properties, Chemical properties

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