Radiation polychromatic

The volume of defects is calculated using intensity evaluation. Considering the polychromatic radiation of microfocus X-ray tubes the X-ray beam is represented by an energy dependent intensity distribution Io(E). The intensity Ip behind a sample of thickness s is given by integrating the absorption law over all energies ... 

In world practice RCT application is considered to the decision of control of the high density objects. The particular feature of RCT is the possibility of the reception of the quantitative information. Besides, the absence of characteristic to X-ray CT result distortions, which are caused by variation of an average value of polychromatic radiation energy, when it passes through an article, promotes the increase of accuracy characteristics of radionuclide CT... 

One instrumental limitation to Beer s law is the use of polychromatic radiation instead of monochromatic radiation. Consider a radiation source that emits two wavelengths of... 

Figure 18.5 Schematic view of a diffraction experiment, (a) A narrow beam of x-rays (red) is taken out from the x-ray source through a collimating device. When the primary beam hits the crystal, most of it passes straight through, but some is diffracted by the crystal. These diffracted beams, which leave the crystal in many different directions, are recorded on a detector, either a piece of x-ray film or an area detector, (b) A diffraction pattern from a crystal of the enzyme RuBisCo using monochromatic radiation (compare with Figure 18.2b, the pattern using polychromatic radiation). The crystal was rotated one degree while this pattern was recorded.

The advantages of using polychromatic radiation from a reactor source, coupled with Laue diffraction methods, have been investigated by McIntyre et al. for high-pressure studies [194]. Using a 0.5-mm crystal in a moissanite anvil pressure cell... 

Technically speaking, the sample is irradiated for a few microseconds with an intense pulse containing all frequencies included in the domain to be sampled. This can be compared to a polychromatic radiation source (like comparing a polychromatic to a monochromatic light source). For example, when working at 300 MHz, the frequency range has to be at least 6000 Hz in order to irradiate all the protons irrespective of their environment. Under these conditions, a small fraction of each type of proton (but not all the protons) will absorb the resonance frequency. 

A major recent innovation has been to use substrates that are unreactive but may be activated by, for example, photolysis (see Chapter 6). This has necessitated the introduction of crystallographic procedures that can gather data in fractions of a second, rather than the minutes or hours conventionally used. Conventional protein crystallography uses a beam of monochromatic x-rays. An older technique that has been reintroduced is that of von Laue, which uses a spectrum of polychromatic radiation. An intense beam from a synchrotron, spanning wavelengths from 0.25 to 2.5 A, enables data for the Laue method to be taken over a fraction of a second.46,47... 

Most results, particularly those obtained in the last decade, have been attained by fast flash techniques, usually using various laser sources of monochromatic radiation. Such methods can provide information on the elementary photochemical and photophysical deactivation steps. For some practical applications, it is more favorable to work with continuous and/or polychromatic radiation. In this article both kinds of results are evaluated. 

The Laue method, employing polychromatic radiation is no longer important as a tool for structure determinations. Laue photographs are... 

In contrast, previous studies with LP Hg lamps indicated that a very high UV fluence Hq of up to 8000 mJ cm is required to inactivate Cryptosporidium. This observation was initially assigned to the much lower irradiance E of LP Hg lamps compared with that of MP Hg lamps or to wavelength effects (Bukhari et al, 1999). LP Hg lamps can be treated as being almost monochromatic UV-C sources ( max= 253.7 nm) whereas MP Hg lamps emit polychromatic radiation in the germicidal range between 200 and 300 nm (cf Fig.s 4-5 and 4-6). 

The LVRPA for polychromatic radiation is calculated from the values of the monochromatic radiation intensity as... 

Alfano, O.M., Romero, R.L., and Cassano, A.E. A cylindrical photoreactor irradiated from the bottom. 111. Measurement of absolute values of the local volumetric rate of energy absorption. Experiments with polychromatic radiation . Chem. Eng. Sci. 41,1163 (1986). 

In many spectrometric instruments, the monochromator is based on prism optics (figure 7.6). This is particularly true of cheaper instruments. When a beam of polychromatic radiation passes through a prism, the light is refracted from its original path. The higher the frequency of the radiation, the greater... 

For polychromatic radiation Eq. (1) must be written in the form of an integral covering all the frequencies ... 

In the case of a polychromatic radiation source with a constant spectral composition, it would be expected that the quantity S[ would be expressed by a relationship somewhat more complex than Eq. (6.5), but it could be shown that Soo can be expressed as... 

In the case where polychromatic radiation sources are used, the photochemical quantum yields should be independent of the wavelength. However, this is a condition that is very difficult to achieve, and requires specific conditions that are discussed... 

Chemical actinometers are suitable for the determination of intensities of polychromatic radiation sources if the following two requirements are met ... 

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