Ferrocyanide bands

B) In-phase spectrum after phase rotation of solution ferricyanide and ferrocyanide bands into the quadrature channel. Reprinted from Ref. [30] with permission. 

Figure 21.24. (a) Magnitude (dashed line) and phase (solid line) spectra of ferricyanide and ferrocya-nide with hexacyanoferrate adsorbed on the electrode surface (b) in-phase spectrum after phase rotation of solution-phase ferricyanide and ferrocyanide bands into the quadrature channel. 10 mM ferrocyanide 1 Hz modulation frequency potential modulation limits, 0.02 to 0.42 V versus SCE. (Reproduced from [20], by permission of the American Chemical Society copyright 1997.)... 

The energy levels in the solution are kept constant, and the applied voltage shifts the bands in the oxide and the silicon. The Gaussian curves in Figure 4b represent the ferrocyanide/ferricyanide redox couple with an excess of ferrocyanide. E° is the standard redox potential of iron cyanide. With this, one can construct (a) to represent conditions with an accumulation layers, (b) with flatbands, where for illustration, we assume no charge in interface states, and (c) with an inversion or deep depletion layer (high anodic... 

A coloured charge transfer complex formed by absorption of ferrocyanide at the surface of Ti02 particles and electrodes, on photo-excitation injects electrons into the conduction band of Ti02 the conduction band electrons can be used to generate a photocurrent (Gratzel, 1987)... 

Reduction of Fe(CN)g ions at n-type semiconductor ZnO electrodes involves the conduction band with reaction orders 1 and 0 with respect to fer-ricyanide and ferrocyanide ions, respectively [55]. The electrode reaction can be described by a simple model of direct electron transfer from the conduction band with no surface states being involved. The potential distri-... 

Another example of pigment identification by IR microspectroscopy is shown in Figure 10. The bottom spectrum was obtained from a blue pigment from MS 972 (Archaic Mark) the top spectrum is a reference spectrum of Prussian blue. The band corresponding to the C=N of ferric ferrocyanide is common to both spectra. Replicate spectra of blue pigments removed from different locations in MS 972 indicate that the average frequency of this band is 2083 6 cm"1. The ubiquitousness of an iron blue in this manuscript raises doubts about the authenticity of this manuscript. 

The FT-IR spectra of a 10 mol.dm ferrocyanide solution (at neutral pH) recorded just after irradiation are represented in Fig. 5(a) for different doses Fig. 5(b) highlights the 2090-2140 cm region of those differential spectra. The negative-going band at 2037 cm represents the loss of ferrocyanide. Just after irradiation, Fig. 5(b) shows that two peaks are observed the first one, located at 2115 cm is attributed to Fe(CN)g whereas the second one is located around 2102 cm h This band was attributed to the Fe(CN)5(OH) ion. Let us point out that the wavenumbers of the infrared bands can be relatively easily modeled using nh initio calculations and that these... 

The most striking feature of cytochrome in state IV is that it is not reducible by ordinary reagents such as ascorbate or ferrocyanide. Two forms of cytochrome coexist in equilibrium at alkaline pH state III reducible and state IV not 161). Only the reducible form shows the 695-nm absorption band, which therefore becomes a useful spectroscopic indicator of reducibility 162,163). Apparently the intact methionine-80-iron bond is necessary for reduction of the iron in a folded cytochrome molecule, although ascorbate can reduce the heme iron if the molecule is totally denatured with propanol or urea 164). This suggests that the protein chain in cytochrome has a protective role to prevent the iron from being easily reduced except under controlled conditions. 

Solomon and Bard reported the first such application (74). The ET between aqueous fer-rocyanide inside a micropipet and TCNQ in the outer DCE phase was used for SECM imaging. TCNQ was reduced by ferrocyanide to form TCNQ at the tip. The images of surface topography and redox reactivity of parallel platinum bands on the silicon surface were obtained by scanning a micropipet in a horizontal x-y plane just a few micrometers above the substrate surface. 

B served as a titrant for C and the change of the collector current compared to the collector current in the absence of C was an indicator of (1) the amount of C present in solution and (2) the rate constant of reaction (12.137). Rajantie et al. [328] used ferrocyanide as a titrant which was generated from ferricyanide galvanostatically and detected at the collector band amperometrically. The analyte was ascorbic acid. Good agreement was found between simulation and experiment. 

Calculations of electron transfer rate constants from the energies of intervalence transfer (IT) bands in mixed-valence complexes have provided some interest (Table 1.1). The ion pair formed from paraquat (l,r-dimethyl-4,4 -bipyridine " ), and ferrocyanide, [PQ ", Fe(CN)6 ], shows an IT band from which the activation energy for thermal electron transfer within the ion pair can be derived (Figure 1.1) using Hush s theory to compare spectroscopic and kinetic data [equation (5)]. 

Four rotation speeds are considered for the study of the ferri/ferrocyanide redox reaction 300, 1000, 1500 and 2000 rpm. Figure 4.a presents a comparison between the mean experimental voltammogram at 2000 rpm and the modeled voltammogram, calculated with the best-fit-parameters, and the 95% confidence interval 2cr, with cr the standard deviation of the current in the set of experimental curves. The difference between the experimental and the modeled curve (Figure 4.b) lies in the 95% confidence band. This means that the model is able to describe the experiments appropiately. 

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