Electron fraction

Therefore the NO3 radical is not formed in diluted nitrate solutions because OH does not react with NO. This finding suggests that the OH reacts with molecular HNO3 through H atom abstraction. The formation of NO3 through direct process is in proportion to the electron fraction of nitrate. In nitric acid, NO3 is formed through two formation processes, but, in concentrated nitrate solutions, only direct process plays a role. The direct action of radiation is commonly observed in concentrated solutions and examples are reviewed in Ref. 122. 

Here/w stands for the electron fraction of water in the solution. Thus the electron fraction of the solute is/s = 1 —fw- In addition, G(HN02), G(H2), and G(02) are G-values of HNO2, H2, and O2 formation, respectively, experimentally determined in the solution. Reported G(H2) and G(02) in nitric acid and sodium nitrate solutions are summarized in Fig. 9 [127]. 

Table 2 Typical Concentration of Components in Coal-Fired Flue Gas and Their Electron Fraction...

The energy, or power, of electron beam induced in the flue gas is divided and absorbed by their gas components roughly depending on their electron fraction. Therefore almost all the energy is absorbed by the main components of the flue gas, namely, N2, O2, CO2, and H2O. Table 2 shows a typical concentration of the components in coal-fired flue gas in Japan. The ratio of the total number of electrons in each gas components is also listed in the same table. The energy absorbed directly by the toxic components (SO2 and NO) is negligibly small. For electron beam treatment of flue gas, ammonia gas is added to the flue gas before the irradiation. The amount of ammonia is usually set as stoichiometrically, i.e., 2A[S02] + A[NO], where A[S02] and A[NO] are the concentrations of SO2 and NO intended to be treated, respectively. The concentration of ammonia is usually higher than the initial concentration of SO2 and NO however, it is still far lower than that of the main components. 

The core characteristics do not change appreciably in these diverse models with central densities near 1010 g/cm3, a central electron fraction Yf 0.42, and temperature Tc 0.5 MeV. The central entropy per baryon rises and falls with the core mass, with high values inimical to healthy shocks. 

The most suitable system for studying the VCR effects are transparent solutions with small concentrations of photosensitive additives. While the energy of fast electrons is distributed in proportion to the electronic fraction of each component, the absorption of VCR quanta is selective with respect to additives. As a result, the VCR energy absorbed by an additive can exceed the energy transferred to it by a fast electron, although the relative fraction of energy spent on VCR is small. 

Depends on electron fraction of substrate. Most energy will be deposited in solvent. Incomplete absorption of quantum. 

Excited molecules produced by the radiation may also transfer their energy to other substrates. The yield of hydrogen in the radiolysis of cyclohexane-benzene solutions is considerably lower than would be expected from the electron fraction of each component and the known hydrogen yields for the pure compounds125. 

Fig. 2). The plasma potential depends on the electron temperature, it will thus vary from one gas to another as a function of the ionisation threshold of the gas the lower ith, the greater the electron fraction to be able to ionise the gas, and thus at equilibrium the lower Te and Vp. 

The numbers of electrons in styrene and CCI4 molecules are 56 and 74, respectively. Therefore, the electron fraction of CCI4 in solution is... 

Fig. 24. The likelihood of a DYR r-process for given combinations of the electron fraction Ye and the entropy per baryon s. A SoS-like r-process is expected for a suitable superposition of conditions between the black lines. The results inferred from an initial NSE phase at low s are smoothly connected to those of various nuclear network calculations for high s values. In the latter cases, the assumed expansion timescales imply that the freeze-out of the charged-particle induced reactions is reached after dynamical timescales Tdyn in excess of about 50 - 100 ms. The two dotted lines represent the contours of successful r-processing for Tdyn = 50 ms (left line) and 100 ms (right line) (see [59] for details)...

Fig. 28. Distribution of the r-nuclide abundances derived for a breeze solution obtained with a PNS mass of 1.5M , an initial electron fraction Ye = 0.48, and different values of the mass loss rate (in units of 10-5 M /s). The upper curve corresponds to the SoS r-nuclide abundances normalized to Xi = 1 (see [24] for details, particularly on the selected breeze solution)...

Fig. 29. Density profile (expressed in baryon number density nb and matter density p in a typical 1.4 Mq NS showing the structure of the crust. The values of the electron fraction Ye are given at p = 4 1011,2 X 1012,1013 and 1014 g/cm3...

Recent results of Schnabel [370] do not, however, confirm this view. Copolymers of dimethylsiloxane and phenylmethylsiloxane and copolymers of dimethylsiloxane and diphenylsiloxane of various compositions have been irradiated with 7-rays. Values of GCL were determined for both types of copolymers. With equal concentrations of phenyl groups, the second polysiloxane is less radiation stable than the first, but for both types, the value of Gc L depends linearly on the electron fraction of the dimethylsiloxane units. No protective effect of the phenyl group, in fact, exists. 

Tn a previous paper (14) a study of the yields of free radicals formed by y-irradiating n-hexane adsorbed on silica gel at 77 °K. showed that a transfer of energy occurred from the silica gel to the adsorbed hydrocarbon phase. This transfer was particularly pronounced at very low coverages. A saturation effect was observed the yields of radicals increased rapidly with the amount of hydrocarbon up to the electron fraction of 0.02, then a leveling off occurred. A decrease in the g = 2.0080 signal from the silica gel was observed at the same time, and at the electron fraction of 0.02 this signal had completely disappeared. From the saturation data the number of active sites on the silica gel surface... 

The occurrence of energy transfer has been confirmed by preliminary determinations of the yield of hydrocarbon products formed (15). The dependence of the yields of various products on the amount of n-hexane shows a rapid increase at low hydrocarbon electron fractions. The curves then flatten out demonstrating that the active sites on the silica gel surface have been used up. There is a difference in saturation behavior for various hydrocarbon products the combination of two n-hexyl radicals to form n-dodecane indicates a saturation at an electron fraction of 0.05, whereas the formation of 5-methylundecane from n-hexyl and 2-hexyl radicals reaches saturation first at the electron fraction of 0.2. The same general behavior is observed also for Ci0, C9, and C8 products. 

Figure 1. The strong narrow component of benzene/silica gel first derivative ESR spectrum at 77°K. at the following electron fractions of benzene (a) xt = 0.001, (b) x1 = 0.02, and (c) Xj = 0.06...

Figure 5. Apparent yields of cation (above) and neutral radicals (below) as function of the benzene electron fraction xt. The dashed line represents no interaction. The solid lines are obtained from the equations given in the text...

When the radiolysis in concentrated aqueous solutions is concerned, the solvent H O with an electron fraction of f and solute with f can be assumed... 

Figure 1 Schematic separation of water component with an electron fraction of fw and solute one with fs in concentrated solutions.

Figure 2 The cahnge of the product yields as a function of electron fraction of solute fS in concentrated solution. The upper line describes the sum of the products from water and solute. The lower line indicates that the product is coming only from solute.

Before presenting the radiolysis of several concentrated aqueous solutions, the electron fraction will be briefly discussed. While the electron fraction can be simply defined as a ratio of the number of electrons of the solute to the solution in the same volume, all electrons are not equivalent some bind strongly to the nucleus. Then, it has been proposed that only valence electrons should be calculated [4]. But the values of the fraction from two different calculations are almost the same within a few percent not strongly dependent on the calculation, and thus the simple calculation is taken in the present chapter. 

Figure 4 G(N03 ) as a function of electron fraction of nitric acid or nitrate ions. Total ( ) and fast (O) component in HNO3 and fast one in L1NO3 ( ) andNaNOj (A).

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