Steady-state electron paramagnetic

Direct information about the local solvation structure for the solvated electron in condensed media is scarce, although having an accurate picture of, at least, the ground state of the solvated electron, is important to interpret its properties. Steady-state electron paramagnetic resonance (EPR) and electron spin-echo modulation (ESEM) experiments as well... 

KE Dukes, EJ Harbron, MDE Forbes. Flow system and 9.5 Ghz microwave resonators for time-resolved and steady-state electron paramagnetic resonance spectroscopy in compressed and supercritical fluids. Rev Sci Instrum 68 2505, 1997. 

For irradiation times of J short with respect to the relaxation time of / the NOE extent is independent of the relaxation time of the nucleus and provides a direct measurement of time required to saturate signal J is not negligible compared with t, the response of the system is not linear [18]. The truncated NOE is independent of paramagnetism as it does not depend on p/, which contains the electron spin vector S in the R[m term, and only depends on gkj), which does not contain S. If then the steady state NOE is reached, the value of p/ can also be obtained. This is the correct way to measure p/ of a nucleus, provided saturation of J can be considered instantaneous. In general, measurements at short t values minimize spin diffusion effects. In fact, in the presence of short saturation times, the transfer of saturation affects mainly the nuclei directly coupled to the one whose signal is saturated. Secondary NOEs have no time to build substantially. As already said, this is more true in paramagnetic systems, the larger the R[m contribution to p/. 

When one looks for methods to detect OH, one always has two keep in mind that these radicals are very reactive, and in the presence of substrates their steady-state concentrations are extremely low even at a high rate of OH production. The fact that OH only absorbs far out in the UV region (Hug 1981) is thus not the reason why an optical detection of OH is not feasible. Electron paramagnetic resonance (EPR) must also fail because of the extremely low steady-state concentrations that prevail in the presence of scavengers. The only possibility to detect their presence is by competition of a suitable OH probe that allows the identification of a characteristic product [probe product, reaction (41)]. When this reaction is carried out in a cellular environment, the reaction with the probe is in competition with all other cellular components which also readily react with OH [reaction (42)]. The concentration of the probe product is then given by Eq. (43), where [ OH ] is the total OH concentration that has been formed in this cellular environment and q is the yield of the probe product per OH that has reacted with the probe. 

Bray, R. C., and George, G. N., 1985, Electron paramagnetic resonance studies using pre-steady-state kinetics and substitution with stable isotopes on the mechanism of action of molybdoenzymes, Biochem. Soc. Trans. 13 561n567. 

The identity of the radical ions formed upon steady-state radiation of DNA in low-temperature glasses has been established by means of electron paramagnetic resonance (EPR) spectroscopy [53]. EPR analysis indicates that electrons and holes are localized on a single nucleobase rather than being delocalized over several stacked bases at low temperatures. Radical ion formation is presumed to occur randomly at all four nucleosides. However, EPR studies establish that the electron holes are localized predominately on guanine, which has the lowest gas phase ionization potential and solution oxidation potential (Tables 1 and 3). Yan et al. [54]... 

The resulting glass-ceramics obtained at various experimental conditions consist of a crystalline phase and a residual glassy phase. The nature of the crystalline phase corresponding to different heat treatment and precipitation conditions is determined by X-ray diffraction This together with a detailed spectroscopic study of the steady state fluorescence, absorption, decay dynamics (by means of selective laser spectroscopy) as well as electron paramagnetic resonance reveals the detailed nature of the crystalline phases. 

Cr=crystal Sm=smectic CrSmB = crystal smectic B N=nematic Ch=cholesteric I=isotropic fluorescence = steady state fluorescence SPC = time-resolved single photon counting CPF=circularly polarized fluorescence UV-vis = UV-visible absorption spectrophotometry DSC=differential scanning calorimetry OM = optical microscopy XRD = X-ray diffraction EPR=electron paramagnetic resonance NMR=nuclear magnetic resonance. 

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