Spin dissolved oxygen

Here, is the magnetization of spin i at thermal equilibrium, p,j is the direct, dipole-dipole relaxation between spins i and j, a-y is the crossrelaxation between spins i and j, and pf is the direct relaxation of spin i due to other relaxation mechanisms, including intermolecular dipolar interactions and paramagnetic relaxation by dissolved oxygen. Under experimental conditions so chosen that dipolar interactions constitute the dominant relaxation-mechanism, and intermolecular interactions have been minimized by sufficient dilution and degassing of the sample, the quantity pf in Eq. 3b becomes much smaller than the direct, intramolecular, dipolar interactions, that is. 

A thin film dissolved oxygen sensor was fabricated by entrapping erythrosin B in a sol-gel matrix95. The silica sol-gel doped with the dye was deposited onto the cleaned glass slides by the spin-coating method. The sensor was linear in the most useful range of dissolved oxygen concentrations, up to 9.1 mg l 1 concentration obtained in air saturated water at 20 °C. 

The interaction between nitroxides and oxygen has been used as a basis for measurement of dissolved oxygen, a procedure that may be termed spin-label oximetry. In this approach calibration curves are constructed relating a nitroxide... 

The reductions of H2O2 and O2 by [Ti(EDTA)(H20)], [Ti(H20)6], [Fe(EDTA)] -, [Fe(H20)6], and [Ru(NH3)j2 produce HO radicals with H2O2 as substrate, as detected by spin trapping techniques. The reactions with O2 proceed by both inner- and outer-sphere electron transfer pathways to produce the O J anion. The reduction of O2 by either [Fe(EDTA)] or [Fe2(ttha)] proceeds by an inner-sphere pathway with the subsequent attack of the coordinated O2 either on an adjacent carboxylate moiety or on sacrificial mediators in the solvent cage. [Ru(bpy)3] is quantitatively photooxidized to [Ru(bpy)3] in strongly acidic solutions containing dissolved oxygen. The process is represented by equations(2) and (3). 

In the NOE, the non-equilibrium magnetization of a spin is shared by nearby spins through mutual di-pole-dipole relaxation. Any other relaxation mechanism, if present, attenuates the effect. For example, dissolved paramagnetic oxygen has a deleterious effect on the NOE. It is therefore necessary to have clean solvents and often it becomes necessary to remove the dissolved oxygen for a quantitative estimate of NOEs. 

Dry spinning. The polymer, dissolved in a suitable solvent and filtered, is pressed through spinnerettes and, in an oxygen-free atmosphere, pulled by vacuum through a heated shaft, where the polymer solidifies as the solvent evaporates. The requirements of this process regarding the heat stability of pigments are much less... 

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