Radiation yield, unit

Q is commonly referred as the sensor quantum yield. It gives the fraction of excited molecules that return to the ground state by emitting a photon. The steady-state sensor luminescence Iss is given by the number of photons radiated per unit of time by our sensor when excited by steady-state excitation. Iss is proportional to Q ... 

Yields and Units. The unit of radiation dose used in this text is the Gray (Gy) 1 Gy corresponds to an energy absorption of 1 J/kg of material. Topical applied doses in the field of radiation modification of polymers are in the range of tens of kGy however, in some cases irradiation up to 10 MGy has been required to induce sufficiently large yields of new molecular structures. The yield of radiochemical events is expressed as the G value [written, for example, G(X) for the G value of cross-hnking]. The G-value is defined as the nnmher of products formed for every 100 eV, or 16 aJ, of energy absorbed by the material. Thus, 1 kGy of radiation will produce G x 1.036 x 10 moles of product per gram of irradiated polymer (4). The SI unit for radiation yield is /imol/J, which is equivalent to 10 Gy (29). 

Multiplying the dpa value by the number of atoms per unit volume yields the theoretical number of interstitial atoms formed by the radiation per unit volume of the irradiated substance. 

The emission yield, Ra, defined as the radiation of the spectral line, k, of an element, i, emitted per unit sputtered mass must be determined independently for each spectral line. The quantities g, and Ry are derived from a variety of different standard bulk samples with different sputtering rates. In practice, both sputtering rates and excitation probability are influenced by the working conditions of the discharge. Systematic variation of the discharge voltage, L/g, and current, I, leads to the empirical intensity expression [4.185] ... 

The yield of cross-linking depends on the microstructure of polybutadiene and purity of the polymer as well as on whether it is irradiated in air or in vacuum. The cross-link yield, G(X), has been calculated to be lowest for trans and highest for vinyl isomer [339]. The introduction of styrene into the butadiene chain leads to a greater reduction in the yield of cross-linking, than the physical blends of polybutadiene and polystyrene [340]. This is due to the intra- and probably also intermolecular energy transfer from the butadiene to the styrene constituent and to the radiation stability of the latter unit. 

Before the experiment, the photochemical reactor is filled, for example, with the solvent of the sample solution, and both radiation-absorbing cells are irradi-atedtypically for a period of less than 1 h. Because the cells are not transparent, all the radiation supplied is quantitatively converted to heat. The thermograms (see chapter 9) of units P and R are recorded and integated. The ratio of their areas, respectively Apo and Ro, yields the so-called constant of the instrument, Cx. ... 

This is Planck s famous radiation law, which predicts a spectral energy density, p , of the thermal radiation that is fully consistent with the experiments. Figure 2.1 shows the spectral distribution of the energy density p for two different temperatures. As deduced from Equation (2.2), the thermal radiation (also called blackbody radiation) from different bodies at a given temperature shows the same spectral shape. In expression (2.2), represents the energy per unit time per unit area per frequency interval emitted from a blackbody at temperature T. Upon integration over all frequencies, the total energy flux (in units of W m ) - that is, Atot = /o°° Pv Av - yields... 

In this chapter, the various radiation chemical yields, known as G-values, are defined as follows g(X) is the yield of the species in reactions (6) and (7) G°(X) is the yield of the initial products of water radiolysis at the end of the physicochemical stage and G(X) is an experimentally measured yield. In some publications Gx, rather than g(X), is used to represent the primary yield of the species X. The yields in reactions (6) and (7) are numerically very similar, but one must be sure of the units that are being used to express them. In the older literature, it was common practice to quote G-values without units when the units were in fact molecules (100 eV) ... 

Background Radiation amount of natural radiation detected in the absence of nonnatural radioactive sources Base a substance that yields hydroxide ions in solution or accepts protons Becquerel SI unit for activity equal to one disintegration per second, abbreviated Bq... 

---