Photon irradiation

Because of the high linear energy transfer (LET) of the particles produced by the 10B(n,a)7Li reaction, the production of secondary ions is not enhanced in the presence of oxygen with low-LET radiation such as external photon irradiation, tissues... 

Sensitivity, S, of the thin resists film is defined as the number, N, of a specific reaction occured in one polymer molecule, which forms the film, by one photon irradiated on a unit surface (cm2). In this case quantum yield, , is defined as the number,... 

In spite of the usually low cooling efficiencies (see the exercise above), recent experiments have demonstrated an anti-Stokes cooling from room temperature to 77 K within a certain internal volume of Yb + doped fluorochloride and fluoride glasses under high photon irradiances (Fernandez et ai, 2000). Future practical applications of optical cooling of solids include cooling systems for spacecraft electronics and detectors, as well as for superconductive circuits. 

The concentrations of electrons and holes in the conduction and valence bands, n and p, in the photostationary state under photon irradiation are expressed, respectively, in Eqn. 10-1 ... 

Fig, 10-1. Splitting of Fermi level, cnsci, into both quasi-Fermi level of electrons, bCp, and quasi-Fermi level of holes, pSp, in photoezcited semiconductors (a) in the dark, (b) in photon irradiation. SC = semiconductor hv = photon energy. 

Thus, photoexcitation permits those electron transfer reactions to occur which are thermodynamicadly impossible in the dark, provided that the photon irradiation shifts the energy level of interfacial electrons (or holes) in the anodic (or cathodic) direction and produces the thermodynamic affinity for the reactions. 

With n-type semiconductor electrodes, the anodic oiQ en reaction (Euiodic hole transfer) will not occur in the dark because the concentration of interfacial holes in the valence band is extremely small whereas, the same reaction will occur in the photon irradiation simply because the concentration of interfadal holes in the valence band is increased by photoexcitation and the quasi-Fermi level pEp of interfadal holes becomes lower than the Fermi level the o en redox... 

The flat band potential of semiconductor electrodes is determined by the potential across the compact las r at the electrode interface and is characteristic of individual semiconductor electrodes. For semiconductor electrodes in the state of band edge level pinning, the potential across the compact layer remains constant and independent of the electrode potential. For some semiconductor electrodes, however, photon irradiation changes the potential across the compact layer and, hence, shifts the flat band potential of the electrode. 

An example of the effect of photon irradiation on the flat band potential is shown in Fig. 10-18 this figure compares a Mott-Schott plot with the anodic polarization curve of the dissolution reaction of a semiconductor anode of n-type molybdeniun selenide in an acidic solution in the dark and in the photoexcited conditions. In this example photoe dtation shifts the flat band potential from Em in the dark to pii) in the photoexcited state is about 0.75 V more positive than Em. This photo-shift of the flat band potential, Emi )-Em, corresponds to the change in the potential, of the compact layer due to photoexcitation as defined in Eqn. 10-23 ... 

I. In reference to a spectral feature, the scalar or magnitude of that feature. 2. Chromatic purity. 3. The magnitude of a particular force or energy per unit (e.g., surface, charge, mass, time, volume, etc.). 4. Synonym for photon irradiance. 5. Synonym for fluence rate. 6. Synonym for irradiance illuminance. 7. Synonym for radiant power. 8. Symbohzed by /, synonym for radiant intensity. 9. See Magnetic Field Strength. 10. See Electric Field Strength. 

Table 5 Selected CT solids having switching behavior under electric field and/or photon irradiation are compared with the sliding SDW ... 

Mechanism CT solid Electric field Reference Photon irradiation Reference... 

Conformal Radiation Therapy Photon Irradiation Techniques... 

GROSSWENDT, B. and HOHLFELD, K. (1982). Angular dependence of specified depth dose equivalent quantities in the ICRU sphere for photon irradiation, Radiat. FYot. Dosim. 3, 169-174. 

From the three decay times, which each measurement provides, the main point of interest how is the type I quantity T. It characterizes the dynamics of the relevant electronic state of the cluster size under investigation. The data, therefore, allow us to determine directly the photodissociation probabilities 1/r 1 of the observed clusters excited at the energies of the photon irradiation. The corresponding results reflect the stability of the clusters, as graphically presented in Fig. 26. For all measured cluster sizes the fragmentation probabilities at E = 2.00 eV are smaller than those for the other photon energies (figs. 26a, b). For E = 2.00 eV and E = 2.94 eV the curves of the dependence of the photodissociation probability on the cluster size have similar shapes. In Fig. 26b both curves show a particular instability for Kg, which... 

Since in industrial photochemistry mostly polychromatic light sources are used, photon quantities are relatively difficult to calculate and require knowledge of the spectral distribution of the radiometric quantity measured. Assuming on the other hand that the radiometric measurements do not need to be corrected for the spectral response of the probe, the photon irradiance at a given point within the reactor volume would then be given by Eqs. (39) and (40), respectively. 

Most of the irregular SE s formed by irradiation interact with impurities that are the native irregular SE s of the crystal. Impurities interact with the irradiation products either by their stress field or, if heterovalent, by the electrostatic (Coulomb) field. Photolysis (radiolysis) is found in other than halide crystals as well. In oxides, the production of Frenkel pairs under photon irradiation is negligible. This has been ascribed to the fact that the reaction O2- +0" = 02 is endothermic, whereas the reaction X- +X = is exothermic. 

Figure 2. Top Spectral photon distribution of daylight on a sunny day. The distribution remains qualitatively similar on cloudy days with the total photon irradiance (i.e., Ep) in the region 400-800 nm reduced by a factor of up to 10. Bottom The spectral photon distribution under a dense patch of ivy leaves near to the ground surface, measured on the same day as the spectrum on top. Not only is the total photon irradiance (Ep) reduced by a factor of approx. 100 by the leaves, but also the spectral distribution is markedly altered, in particular at around 700 nm and above. (Both spectra from Smith [13].)...

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