Radiation chemical yield composites

In most Materials Characterization experiments the sample is subjected to some kind of radiation electromagnetic, acoustic, thermal, or particles (electrons, ions, neutrons, etc.). The surface analysis techniques usually require a high vacuum. As aresult of interactions between the solid (or liquid) and the incoming radiation abeam of a similar (or a different) nature will emerge from the sample. Measurement of the physical and/or chemical attributes of this emerging radiation will yield qualitative, and often quantitative, information about the composition and the properties of the material being probed. 

The products of radiolysis of a Ng—Og mixture include NOg, NgO, NO, and ozone. The yields of these products depend on pressure and mixture composition. The correlation between the energy yields of the radiation-chemical formation of ozone and of nitrogen dioxide in the Ng—Og system has been studied earlier [109]. The changes in G(NOg) and G(03) as a function of mixture composition are shown in Table 13. 

You are probably aware of some of the damaging effects of ultraviolet radiation from the Sun if you have ever suffered from a sunburn. Overexposure to ultraviolet radiation also is harmful to plants and animals, lowering crop yields and disrupting food chains. Living things can exist on Earth because ozone, a chemical in Earth s atmosphere, absorbs most of this radiation before it reaches Earth s surface. A chemical is any substance that has a definite composition. Ozone is a substance that consists of three particles of oxygen. 

The spectra shown in Figure 6.1 require 14 excited vibrational states of the ground electronic state to be taken into account to explain all the fine structure that is seen. The researchers analysing the spectra conclude that H2 in this interstellar region is being formed on dust particles and then dissociated by intense UV radiation. So the spectra have yielded information on the conditions in this region of space, the presence of dust and the composition of the interstellar gas in chemical terms. 

Vibrational spectroscopy provides for the analysis of the chemical composition, molecular structures, conformations, and interactions in a sample. Two methods that are commonly used for molecular vibrational analysis are infrared (IR) and Raman spectroscopy. One of the limitations of the former, which relies on measuring the absorption or reflection of mid-IR radiation by molecular bonds, is the low spatial resolution afforded by the technique, allowing only chemical information from a large group of cells to be obtained. Raman spectroscopy, on the other hand, offers high spatial resolution subcellular chemical analysis of an individual cell. It relies on the scattering of photons by molecular bonds, which yields chemical information about the molecular stmcture and conformations in the sample. It has seen an increase in its use for biological studies because it offers many attractive features. The method is able to... 

One of the main tasks of nuclear-reactor safety research is assessing the integrity of the reactor pressure vessel (RPV). The properties of RPV steels and the influences of thermal and neutron treatments on them are routinely investigated by macroscopic methods such as Charpy V-notch and tensile tests. It turns out that the embrittlement of steel is a very complex process that depends on many factors (thermal and radiation treatment, chemical compositions, conditions during preparation, ageing, etc.). A number of semi-empirical laws based on macroscopic data have been established, but unfortunately these laws are never completely consistent with all data and do not yield the required accuracy. Therefore, many additional test methods are needed to unravel the complex microscopic mechanisms responsible for RPV steel embrittlement. Our study is based on experimental data obtained when positron annihilation spectroscopy (PAS) and Mdssbauer spectroscopy (MS) were applied to different RPV steel specimens, which are supported by results from transmission electron microscopy (TEM) and appropriate computer simulations. 

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