Radiation efficiency

The sensitizers display a crucial role in harvesting of sunlight. To trap solar radiation efficiently in the visible and the near IR region of the solar spectrum requires engineering of sensitizers at a molecular level (see Section 9.16.3).26 The electrochemical and photophysical properties of the ground and the excited states of the sensitizer have a significant influence on the charge transfer (CT) dynamics at the semiconductor interface (see Section 9.16.4). The open-circuit potential of the cell depends on the redox couple, which shuttles between the sensitizer and the counter electrode (for details see Section 9.16.5). 

SENSITIVITY Energy density Exposure rate Exposure environment Developing Post-exposure treatment Radiation efficiency Molecular weight... 

The ovens used to melt the powder on the part can be convection, infrared or combination (hybrid) ovens. IR or combination (IR/convection) ovens are most widely used. IR radiation efficiently heats the surface without a rise in the core temperature of the part. Surface temperatures usually range from 100-120°C (212-250°F). 

The industrial PNC process is based on the development of efficient photoreactors. Toray designed an immersion lamp with a high radiation efficiency and capacity as well as long life. In order to remove the short-wave radiation below 365 nm (which contributes to tar formation on the lamps) either an absorbent is added to the cooling water, or the light source is surrounded by a glass filter264. 

The intensity of a Raman signal is governed by a number of factors, including incident laser power, frequency of the scattered radiation, efficiency of the grating (in the case of dispersive instruments) and detector, absorptivity of the materials involved in the scattering, molar scattering power of the normal mode, and the concentration of the sample. This situation is further complicated by the fact that many of these parameters are frequency-dependent, as indicated in the following equation ... 

The radiation efficiency is higher than in other designs. 

The molecular weight of polymers prepared using UV radiation is always lower than that of the thermally synthesized ones. Indeed, the radiation efficiency is higher than the thermal efficiency in the homolytic scission of hydrogen peroxide. 

Apart from the determination of polymer yield (in %), just as in conventional polymerization, in the case of radiation-induced polymerization, the radiation-chemical yield Gp is used, which makes it possible to determine the radiation efficiency of the process. For... 

Mital, R., Gore, J. R, Viskanta, R., and Singh, S. "Radiation Efficiency and Structure of Flames Stabilized Inside Radiant Porous Ceramic Burners." In Combustion and... 

The lamp phosphor converts the 254 and 185 nm radiation into visible light (Fig. 6.1). It is in direct contact with the mercury discharge which rules out many potential candidates. For example, sulfides cannot be used in lamps since they react with mercury. A lamp phosphor should absorb the 254 and 185 nm radiation strongly and convert the absorbed radiation efficiently, i.e. their quantum efficiency should be high. 

The green-emitting ion in the tricolor lamp is Tb. Its first allowed absorption band is 4/ -> 4/ 5d(Sect. 2.3.4.). It often lies at too high energy to make 254 nm excitation effective. In order to absorb the 254 nm radiation efficiently, a sensitizer has to be used. For this purpose the Ce ion is very suitable. Its 4/-> 5dtransition is situated at lower energy than the corresponding 4/ -> AfSd transition of Tb ". Table 6.1... 

There is some experimental evidence to indicate that much of the enhancement is associated with surface roughness (local microstructures) in the range of 1 to 100 nm. At resonance with th microparticle modes the local electric field at the incident frequency (h L) becomes large near and on the particle surface. Furthermore, the re-radiation efficiency of Raman active molecules situated near the surface also becomes enhanced when the inelastically scattered frequency (hco,) is also in resonance with these microparticle modes. The Raman scattering intensity of the adsorbed molecule is then given by... 

By changing the sampling arrangements. Special care has to be taken to collect the Raman radiation efficiently, especially for small samples. A special sample cell has been developed which uses a spherical cuvette with the sample at the centre [40]. 

However, perhaps the most noteworthy is that in spite of the fact that one of the surface waves has a peak exceeding that of the Hoquet currents peak by about 5dB, the highest value of the scattering pattern is almost 20 dB below the peak of the Floquet pattern. In other words, the radiation efficiency of the surface waves is considerably lower than that of the Floquet currents. Or we may alternatively state that the radiation resistances associated with the surface waves are considerably lower than the one associated with the Floquet mode. Inspection of Fig. 4.5e shows this statement to be correct. This observation will later prove crucial when we try to control the radiation from the surface waves without significantly attenuating the one from the Floquet mode. 

Absorb radiation efficiently. Avoid contaminants, pigments, additives, or resinous materials which compete for the available radiation. Choose a photoinitiator which has the optimum balance of extinction coefficients for the given application. In pigmented systems, choose photoinitiators which absorb strongly at wavelengths where the pigment absorbs weakly. In many cases, a blend of two photoinitiators will make better use of the available radiation, as will be discussed later. 

Use the absorbed radiation efficiently to form free radicals. Avoid components which might quench (deactivate the excited state of) the photoinitiator, such as styrene or conjugated double bonds (5). The ideal photoinitiator will not undergo side reactions which produce inactive free radicals. 

A heat exchanger is composed of heat radiation fins and a fan. The coolant flowing in the heat exchanger radiates heat out through the fins, and the radiated heat is sent out of the fuel cell system by the fan. The radiation fins are made with thin metal sheets with large surface areas in order to achieve high heat radiation efficiency. Without the fan, the air temperature around the fins will quickly get close to the coolant temperature after the fuel cell is running for a short time because the heat accumulates inside the fuel cell system s enclosure. Then, the heat that is able to radiate out of the fins will become smaller... 

Efficiency to maximize the radiated power, the antenna designer wiU aim at a large radiation efficiency. As previously discussed, the total efficiency is the product of two terms. The first one, the impedance mismatch factor M, can he maximized by minimizing the reflection coefficient. The second term, the conductive-dielectric efficiency Ced can be maximized by using textile materials with low ohmic and dielectric losses, ie, electrotextiles with high conductivity and textile dielectric substrates with low tan 6. 

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