Radiation absoiption

Thus, given the preferential radiation absoiption in the lower wavelengths, a change in shape of the transmission spectra is observed for both catalysts, lypical transmission spectra for Hombikat UV-100 using the BL lamp ai e illusti ated in Figure 4.32. These measurements were taken at window four, at 5.5 cm from the lamp surface. The catalyst concentration was varied from 0 to 0.258 g L . ... 

Beer s absorption law (1) for the penetrating radiation is used to correlate the penetrated wall thickness (w) and the radiation dose I (lo - radiation dose at w=0, p - absoiption coefficient) ... 

C Define emissivily and absoiptivity. What i.s Kirch-hoff s law of radiation ... 

Radiation is emitted by every point on a plane surface in all directions into the hemisphere above the surface, ITie quantity that describes the magnitude of radiation emitted or incident in a. specified direction in space is the radiation intensity. Various radiation flu.xes such as emissive power, irradiation, and ra-diosity are expressed in terms of intensity. This is followed by a discussion of radiative propertie.s of materials such as emissivity, absoiptivity, reflectivity, and transmissivity and their dependence on wavelength, direction, and lemperatiire. The greenlioiijie effect is presented as an example- of the con.sequenccs of the wavelength dependence of radiation properties. We end tliis chapter with a dis cussion of attno.spheric and solar radiation. 

A I see spectroscopy as the use of absoiption, emission, or scattering of electromagnetic radiation by matter to study qualitatively... 

Charge transfer complexes Complexes that are made up of an electron donor group and an electron acceptor group absoiption of radiation by these complexes involves a transfer of electrons from the donor to the acceptor. 

Atomic absoiption spectroscopy (AAS) is probably still the most widely employed of all the atomic methods because of its simplicity, effectiveness and relatively low cost. A Tine source of radiation is required for AAS (they do not employ a continuous source of radiation) hence a complete spectrum is not obtained. The sources (which are changed depending on the element of interest) emit certain lines of radiation that have the same wavelength as that of the absorption peak of the analyte of interest. 

Fig. 5.64. Radiation pathways of beams reflected at the two interfaces of a thin film with re-fractive index n and absoiption coefficient ky in between medium with no

The primary quantum yield (Primary Q.Y.) establishes the number of molecules degraded from a primary process or event that involves direct absoiption of radiation over the number of photons absorbed (Cassano et al., 1995 and Davydov et al., 1999). Cassano et al., (1995) argue that according to the second law of photochemistry, the absorption of light by a molecule is a one-quantum process. Therefore a quantum yield factor involving the sum of all primary processes must be less than or equal to unity and this as a result that the energy absorbed by the molecule is partially lost by re-emission, collision or other processes (Alfano and Cassano, 1988). 

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