Radiation sources, high intensity

With the development of very high intensity radiation sources, the reactions of the primary species can now be followed directly (16). Both optical spectra and electrical conductivity have been used to follow chemical reactions induced by pulse radiolysis. e aq and OH radicals have optical absorptions that can be easily followed. H atoms cannot be... 

Radiation Dosimetry in Relation to High Intensity Radiation Sources... 

The radionuclides come in the form of calibration/reference sources, and as inorganic compounds and labeled organic compounds. They are packed in various ways, most commonly in a glass ampoule packed in a small aluminum can. To reduce the surface radiation dose rate (cf. Ch. 18) for high intensity radiation sources (usually > 10 MBq) the can is put in a lead block which is packed in a wooden crate for shipment. Opening of the aluminum can and glass ampoule may require remote control and should be done only by experienced, licensed personnel. 

Like many of the topics discussed in this book, photochemical reactions are most likely to be used in niche applications for commercial and environmental reasons. Unless there is a major breakthrough in reactor and lamp design, widespread use of this technology is unlikely. Perhaps the best hope of producing high-intensity monochromatic sources of radiation rests with lasers, but currently equipment costs are too high to justify their use for commercial chemical production. 

Preparation for X-ray Analysis. Lattice constants are calculated from patterns obtained on powder samples with a Norelco diffractometer using monochromatic radiation (AMR-202 Focusing Monochromator) from a high-intensity copper source. The crystals are powdered with a diamond mortar and pestle, and the powder passed through a 74-/ sieve. Accurate lattice constants are calculated from the x-ray data. 

For EXAFS and particularly for XANES, data analysis is complex. The oscillation frequency/bond distance dependence means that extensive use is made of Fourier transform analysis. Most applications to date have been in the EXAFS region. In order to acquire sufficiently strong signals in a reasonable time, use has to be made of high-intensity photon fluxes, which are available at synchrotron facilities. These provide a broad-band tuneable source of high-intensity radiation, but the reduced number of facilities limits widespread dissemination of the technique. Reflection (fluorescent detection) mode is usually preferred to transmission. Experiments can be conducted in any phase, and the probing of electrode surfaces in situ is an important application. 

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