Conduction electron spin resonance studies

Short-lived organic radicals, electron spin resonance studies of, 5, 53 Small-ring hydrocarbons, gas-phase pyrolysis of, 4, 147 Solid state, tautomerism in the, 32, 129 Solid-state chemistry, topochemical phenomena in, 15, 63 Solids, organic, electrical conduction in, 16, 159 Solutions, reactions in, entropies of activation and mechanisms, 1, 1 Solvation and protonation in strong aqueous acids, 13, 83 Solvent effects, reaction coordinates, and reorganization energies on nucleophilic substitution reactions in aqueous solution, 38, 161 Solvent, protic and dipolar aprotic, rates of bimolecular substitution-reactions in,... 

Reactions of KI with Cl2 and of NaCl and KC1 with F2 have been studied [92, 93, 103, 104] and a variety of properties have been measured as a function of the extent of reaction in the conversion of CuCl to CuCl2 by reaction with Cl2 [89, 105, 106]. A consistent feature of all these studies is that, together with or sometimes preceding nucleation and growth of new solid phases, the solid reactant is damaged by electron withdrawal, leading to the formation of various types of electronic defect of the trapped-hole or V-centre type. Studies of electrical conductivity, electron spin resonance spectra and UV absorption are useful in elucidating the behaviour of these defects. 

Effective molarities of intramolecular reactions, 17, 183 Electrical conduction in organic solids, 16, 159 Electrochemical methods, study of reactive intermediates by, 19, 131 Electrochemistry, organic, structure and mechanism in, 12, 1 Electrode processes, physical parameters for the control of, 10, 155 Electron spin resonance, identification of organic free radicals by, 1, 284 Electron spin resonance studies of short-lived organic radicals, 5, 23 Electron-transfer reaction, free radical chain processes in aliphatic systems involving an, 23, 271... 

The Peierls instability and the high degree of one-dimensionality are observable in a whole series of different experiments. These include the dc conductivity in low applied fields (see Sect 9.6.1 and Fig. 1.13), the diffuse reflections of the Ikp superlattice in X-ray scattering (Sect 9.6.2), the reflection spectra from the FIR up to the UV spectral ranges (Sect 9.6.3), the magnetic susceptibihty (Sect 9.6.4), the conduction electron spin resonance, and nuclear resonances (Sect 9.6.5), as well as the nonlinear electrical conductivity at high apphed electric fields or at high frequencies (Sect. 9.6.6). Most of these methods are also employed for the study of the other radical-ion salts, e.g. TTF-TCNQ or the DCNQl salts. They will therefore be treated as examples in this Sect 9.6. 

Traditionally, charge transfer mechanisms have been studied by such methods as conductivity, the Hall effect, and thermoelectric effect. Details of these applications may be found in Experimental Methods of Physics, Vol. 6, Pt. b (12), the article on ionic conductivity by Lidiard (70), and in many of the original papers quoted. More recently, techniques such as electron spin resonance (13), dielectric loss and pulsed photoconductivity methods (5—8) have been used to study semiconduction in organic materials. 

Behrens G, Bothe E, Koltzenburg G, Schulte-Frohlinde D (1980) Formation and structure of 1,1-di-alkoxyalkene radical cations in aqueous solution. An in situ electron spin resonance and pulse conductivity study. J Chem Soc Perkin Trans 2 883-889... 

Wardman P, Dennis MF, Everett SA, Patel KB, Stratford MRL, Tracy M (2003) Radicals from one-electron reduction of nitro compounds, aromatic N-oxides and quinones the kinetic basis for hypoxia-selective, bioreductive drugs. Biochem Soc Symp 61 171-194 Warman JM, de Haas MP, Hummel A, van Lith D, VerberneJB, Loman H (1980) A pulse radiolysis conductivity study of frozen aqueous solutions of DNA. Int J Radiat Biol 38 459-459 Warman JM, de Haas MP, Rupprecht A (1996) DNA a molecular wire Chem Phys Lett 249 319-322 Warters RL, Lyons BW (1992) Variation in radiation-induced formation of DNA double-strand breaks as a function of chromatin structure. Radiat Res 130 309-318 Warters RL, Hofer KG, Harris CR, Smith JM (1977) Radionuclide toxicity in cultured mammalian cells Elucidation of the primary site of radiation damage. Curr Top Radiat Res Q 12 389-407 Weiland B, Huttermann J (1998) Free radicals from X-irradiated, dry and hydrated lyophilized DNA as studies by electron spin resonance spectroscopy analysis of spectral components between 77 K and room temperature. Int J Radiat Biol 74 341-358 Weinfeld M, Soderlind K-JM (1991) 32P-Postlabeling detection of radiation-induced DNA-damage identification and estimation of thymine glycols and phosphoglycolate termini. Biochemistry 30 1091-1097... 

Mesuere et al. [99] and Gerringa et al. [100] have reviewed methods for the determination of copper in soils. Residual copper(II) complexes have been determined in soil by electron spin resonance spectroscopy. Fast neutron activation analysis has been studied [101] as a screening technique for copper and (zinc) in waste soils. Experiments were conducted in a sealed tube neutron generator and a germanium y-ray detector. 

The charged quasiparticles can be probed by electrical dc conductivity measurements (for polarons), magnetic susceptibility (for polarons and bipolarons), electron-spin resonance (ESR) (for polarons) and optical measurements (for polarons and bipolarons). As ESR is well suited for studying spin-carrying polarons, optical modification of the ESR (optically detected magnetic resonance ODMR) can be applied to link the emissive or absorbing properties of the polymer with its spin state. 

Later Bjerrum s theory was supported by the work of Kraus [138], who showed importance of the dielectric constant, and Atherton [139], who demonstrated the existence of ion pairs using electron spin resonance spectroscopy. The formation of ion pairs may be studied by various methods conductance studies, UV-visible spectrometry, IR spectrophotometry, partition, distribution, or solvent extraction. The lifetime of ion pairs was determined to be at least 10 sec, which is equivalent to about 10 molecular vibrations, demonstrating that ion pairs can be considered as independent species [140]. Today, the ion-pair formation as independent species is widely accepted. 

The proceedings of a conference on metal-ammonia solutions have been published, featuring reviews of the physical properties of dilute and concentrated solutions, electrical, n.m.r., i.r., and Raman spectroscopic studies of diffusion, the solvated electron, kinetics, and solution structure."" Electron spin resonance in metallic Li-NHa systems has been investigated from 12 to 296 K. In the liquid solutions and in the cubic phase of Li(NH3)4 the conduction e.s.r. lineshapes are in agreement with theory. To a good approximation the solvated ions are the only spin scatterers in the liquid state. The paramagnetic susceptibility of liquid Li(NH3)4 indicates that the concentration of localized moments is low and they order antiferromagnetically below 20 K." ... 

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