CIDEP Chemically Induced Dynamic Electron

Both CIDNP and ESR techniques were used to study the mechanism for the photoreduction of 4-cyano-l-nitrobenzene in 2-propanol5. Evidence was obtained for hydrogen abstractions by triplet excited nitrobenzene moieties and for the existence of ArNHO, Ai N( )211 and hydroxyl amines. Time-resolved ESR experiments have also been carried out to elucidate the initial process in the photochemical reduction of aromatic nitro compounds6. CIDEP (chemically induced dynamic electron polarization) effects were observed for nitrobenzene anion radicals in the presence of triethylamine and the triplet mechanism was confirmed. 

Appropriate modifications of the ESR spectrometer and generation of free radicals by flash photolysis allow time-resolved (TR) ESR spectroscopy [71]. Spectra observed under these conditions are remarkable for their signal directions and intensities. They may be enhanced as much as one hundredfold and may appear in absorption, emission, or in a combination of both modes. These spectra indicate the intermediacy of radicals with substantial deviations from equilibrium populations. Significantly, the splitting pattern characteristic for the spin density distribution of the intermediate remains unaffected thus, the CIDEP (chemically induced dynamic electron polarization) enhancement facilitates the detection of short-lived radicals at low concentrations. 

CIDEP chemically induced dynamic electron polarization... 

CIDEP (Chemically Induced Dynamic Electron Polarization) Non-Boltzmann electron spin state population produced in thermal or photochemical reactions, either from a combination of radical pairs (called radical-pair mechanism), or directly from the triplet state (called triplet mechanism), and detected by ESR spectroscope... 

This organometallic radical product could, however, be detected by irradiation in glassy frozen matrices [34]. The alkyl radicals, as very short-lived metal-free products, could be observed and analyzed by FT-ESR with respect to CIDEP (chemically induced dynamic electron polarization) effects [34]. 

CIDEP chemically induced dynamic electron polarization CIDNP chemically induced dynamic nuclear polarization e electron... 

CIDEP = Chemically Induced Dynamic Electron Polarization. For a review see F. J. Adrian, in Chemically Induced Magnetic Polarization, edited by L T. Muus, P. W. Atkins, K. A. McLauchlan, and J. B. Pedersen (Reidel, Dordrecht, 1977), Chap. 5, pp. 77-105. 

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