Oxidation states identification

Analytical methods based on coprecipitation techniques are used to determine the oxidation-state speciation of the light actinides, which can occur in solution in multiple oxidation states. An example of such a separation is the ability to selectively remove tri-and tetravalent actinide cations from penta- and hexavalent species by coprecipitation with lanthanide fluoride (Choppin 1985). Lanthanide fluoride eoprecipitation has been used to perform oxidation-state identification in ground-water samples (e.g., Nash et al. 1988). There are numerous other examples of the application of the coprecipitation technique to environmental samples. 

Chemical oxidation state identification from XAES features is accomplished using the concept of the Auger parameter (o ), which is defined as the distance between the most prominent photoelectron emission and Auger features from the same element in an XP spectrum ... 

One problem that should be of particular interest for separation processes is the identification and kinetic characterization of the reactive radicals that occur when strong nitric acid solutions are subject to ionizing radiation. The important reducing radical in such solutions is the H atom. There are presently no direct measurements of the rate of reduction of H atoms with any Pu oxidation state. 

In the case of oxidized Fe2S2 the two ions are equal, so there is no valence trapping. The same holds, in principle, for [Fe3S4l". However, here the three ions are always nonequivalent, i.e., two are more strongly coupled together than the third, or all three have different coupling values (42, 83, 84). The spectrum is reported in Fig. 2C. The nonequivalence of the three Fe atoms may lead to their identification within the protein frame. In the case of [Fe4S4p all the irons are equivalent with oxidation state 2.5+ (85, 86). 

The elemental composition, oxidation state, and coordination environment of species on surfaces can be determined by X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES) techniques. Both techniques have a penetration depth of 5-20 atomic layers. Especially XPS is commonly used in characterization of electrocatalysts. One common example is the identification and quantification of surface functional groups such as nitrogen species found on carbon-based catalysts.26-29 Secondary Ion Mass spectrometry (SIMS) and Ion Scattering Spectroscopy are alternatives which are more surface sensitive. They can provide information about the surface composition as well as the chemical bonding information from molecular clusters and have been used in characterization of cathode electrodes.30,31 They can also be used for depth profiling purposes. The quantification of the information, however, is rather difficult.32... 

Of significance is the fact that the chemical shift of the ["TcO (H20)(CN)4] (S = -1350 ppm) is the most shielded reported for a Tc(V) complex to date, the previous lowest shift being for the [99Tc02(CN)4]3 (S = +806 ppm), shown in Fig. 5. This observation underlined the fact that the oxidation state of a Tc center cannot be directly estimated (other than maybe for the identification of Tc(I) complexes) from 99Tc chemical shift, as has been suggested previously (45, 46). 

Astatine, 6 207-223, 31 43-88 as astatate ion, 6 219-220 as astatide ion, properties of, 6 217-218 biochemical compounds of, 6 222 biochemical fate, 31 78 biological behavior, 6 222 31 77-78 biomedical applications, 31 79-83 therapeutic studies, 31 80-81 chemical properties of, 6 216 diatomic, 31 50 distallation, 31 47-48 elementary, 6 218-219 embryotoxicity, 31 78 extraction techniques, 31 47 identification, 31 49 in intermediate oxidation state, 6 219 iodide, 6 218-219 isotopes, 31 43-49 decay, 31 44 half-lives, 31 44 decay and half-lives of, 6 210 experimental methods for, 6 213-216 production and measurement of, 6 209-216... 

We were interested in the change in the oxidation state of Pd (II), incorporated in the zeolite, during heat treatment in oxygen or in vacuo. Hydrogen and carbon monoxide interactions were also studied. The experiments involved two techniques ESR, which provides direct identification of palladium in an ionic state, and IR spectroscopy, which gives information on the superficial structure of the exchanged zeolite and on the adsorbed species. 

The identification of three stable oxidation states for Re2Cl4 [P(C2H5)3]4+ (n = 0, 1, 2) provides an example of a multiple inetal-metal bond serving as a redox center while maintaining a strong bonding interaction in each oxidation state (100). 

Since methionine seems to be bound in both oxidation states, and yet is the more labile axial ligand in the reaction with cyanide ion, the NMR data seem to support that histidine is also an axial ligand in ferri- and ferrocytochrome c. Direct identification of the axial histidine in the... 

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