Absorption oxidation during

Figure 5. Absorption changes during the photochemical oxidation of CoPc(py>2 in CH2CI2 in the presence of 10 M CBr4.

Figure 7. Absorption changes during the electrochemical oxidation of FePc(py)2 in CH2CI2 in the presence of 0.05 M [(Et) N]C10 (1) The unoxidized, neutral species. (2) The spectrum recorded following metal oxidation at 0.69 V vs. see. (3) The spectrum recorded following oxidation of the ring at 0.88 V vs. see...

See also Metallophthalocyanines absorption spectra during electrochemical oxidation, 321-325 absorption spectra during photolysis, 321-325 Iron porphine... 

Another contribution to variations of intrinsic activity is the different number of defects and amount of disorder in the metallic Cu phase. This disorder can manifest itself in the form of lattice strain detectable, for example, by line profile analysis of X-ray diffraction (XRD) peaks [73], 63Cu nuclear magnetic resonance lines [74], or as an increased disorder parameter (Debye-Waller factor) derived from extended X-ray absorption fine structure spectroscopy [75], Strained copper has been shown theoretically [76] and experimentally [77] to have different adsorptive properties compared to unstrained surfaces. Strain (i.e. local variation in the lattice parameter) is known to shift the center of the d-band and alter the interactions of metal surface and absorbate [78]. The origin of strain and defects in Cu/ZnO is probably related to the crystallization of kinetically trapped nonideal Cu in close interfacial contact to the oxide during catalyst activation at mild conditions. A correlation of the concentration of planar defects in the Cu particles with the catalytic activity in methanol synthesis was observed in a series of industrial Cu/Zn0/Al203 catalysts by Kasatkin et al. [57]. Planar defects like stacking faults and twin boundaries can also be observed by HRTEM and are marked with arrows in Figure 5.3.8C [58],... 

In those instances where the sample has undergone extensive chemical reaction such as, for example, oxidation during bleaching, the spectral absorption characteristics of the lignin may have been altered to such a degree as to make measurement of absorbance at 280 nm meaningless. Under these circumstances neither the acetyl bromide method nor any other spectrophoto-metric method represents a viable analytical approach. 

Ruitenbeek, M., Van Dillen, A.J., de Groot, E.M.F., Wachs, I.E., Geus, J.W. and Koningsberger, D.C. (2000) The structure of vanadium oxide spedes on. gamma-alumina an in situ X-ray absorption study during catalytic oxidation. Topics in Catalysis, 10 (3 ) 241-54. 

Oxidation-Reduction Reactions. The various oxidation states of neptunium in the KF solution were obtained by adding the neptunium, which had been adjusted to the desired valence state in dilute acid, to the KF solution. Observations were made of the eflFect of a number of potentially useful oxidizing and reducing agents upon the oxidation state of the neptunium. The valence states of the neptunium ions, IV, V, and VI, were determined by absorption spectra. During the reduction to the III state, the solution color disappeared, and a purple solid was produced. 

The earliest mechanistic proposal related to the formation of diperoxyal-kyl species appears to be that made in 1951 by Neu et al. [188]. It was based on the formation of dicarbonyl products, detected by absorption spectroscopy, during the slow oxidation of pentane and that of other organic compounds. 

Fig. 1.90. (a) Shown are the CO absorption bands during the CO oxidation on Pdi/MgO(100) model catalysts. In these experiments, the samples were annealed to the indicated temperatures and the IR-spectra were recorded at 90 K. (b) Shown is the reaction mechanism of the CO oxidation on a single Pd-atom adsorbed on an F-center, obtained by intensive ab initio calculations... 

Fig. 8. Absorption changes during photooxidation and dark re-reduction of the primary electron donor P (A) and oxidation of cytochrome c (B) following a brief, intense flash. Figure source Parson and Clayton (Straley, Parson, Mauzerall and Clayton) (1973) Pigment content and molar extinction coefficients of photochemical reaction centers from Rhodopseudomonas sphaeroides. Biochim Biophys Acta. 305 606.

Complex II from bovine heart mitochondria was first reported by Doeg et al. (39) to contain a type b cytochrome which shows absorption peaks at 562, 530, and 430 nm in the reduced minus oxidized difference spectrum. Davis et al. ( 4) have recently reported the presence in complex II of a cytochrome which has termed cytochrome 5-557.5 based on the a-band position in the low temperature difference spectrum. This cytochrome shows an a peak at 560-561 nm at room temperature, and this peak is split into two hands at 557.5 and 550 nm at 77°K. This cytochrome, 6-560, is neither reduced nor oxidized during the course of the reaction. The spectral similarity to the cytochrome split from complex III may indicate this cytochrome to be a modified form of cytochrome 6 or bi... 

Oxidation. During the absorption step some oxidation occurs ... 

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