Pulse electron paramagnetic resonance detection

Electron-nuclear double resonance (ENDOR) spectroscopy A magnetic resonance spectroscopic technique for the determination of hyperfine interactions between electrons and nuclear spins. There are two principal techniques. In continuous-wave ENDOR the intensity of an electron paramagnetic resonance signal, partially saturated with microwave power, is measured as radio frequency is applied. In pulsed ENDOR the radio frequency is applied as pulses and the EPR signal is detected as a spin-echo. In each case an enhancement of the EPR signal is observed when the radiofrequency is in resonance with the coupled nuclei. 

Recently, the SP-PLP-electron paramagnetic resonance (EPR) technique has been introduced as a direct method for kt measurement, in which EPR detection is used to trace the decay of radicals after laser pulse initiation.This novel technique has however not yet been applied at high pressures. 

A powerful technique to detect paramagnetic radical species, such as the one-electron reduced 7t-radical anions (Ceo ) and oxidized 7t-radical cation (Ceo ) is electron spin resonance (ESR) (9,10). Studies, regarding the characterization of fullerene intermediates via employing the ESR technique are, however, still somewhat controversial. Absorption spectrophotometry, on the other hand, is been successfully employed in matrix irradiation, silver mirror reduction in tetrahydrofuran (THF), and detection of transients in time-resolved laser photolysis and pulse radiolysis (10,11). 

Electron spin resonance studies of irradiated DNA at 77°K permitted the detection of at least two distinct paramagnetic centers. Pulse radio-lysis technics have been used to study the reaction of DMA and related pyrimidine bases with water radlolysls products. The free radicals produced in animal tissues have kinetic properties that are related to the radiosensitivity of those tissues.In a continuing study of the repair of damaged macromolecules by destruction of free radical sites it was found that transfer of the unpaired electron to a thiol occurred best in acid solution, in which the thiol is undissociated.Transfer to disulfide... 

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