Radiation irradiation

Energetic x rays and gamma rays penetrate tissue well enough so that an external source of such radiations may deliver a relatively uniform dose to all parts of the body. Particulate radiations, on the other hand, penetrate much less readily, especially those with high mass and charge, such as alpha particles. With such radiations, irradiation of deep-seated tissues wUl occur only as a result of internal deposition. 

PVF becomes cross-linked as PVDF and forms a gel fraction when exposed to ionizing radiation. Irradiated PVF exhibits higher tensile strength, and resistance to etching increases with increasing dose but, as in PVDF, the degree of crystallinity and melting point decrease.29... 

Figure 12.21 shows the effect in an n-type semiconductor of promotion of electrons by incident photons and subsequent electrode reactions. This figure should be compared with Fig. 6.9 for an n-type semiconductor without incident radiation. Irradiation facilitates oxidation, a significant overpotential being unnecessary. Figure 12.22 compares schematically what is obtained at semiconductor electrodes with and without incident light. As is to be expected there is no photoeffect (except in rare cases) for potentials more negative than Uft,. 

There is no health risk to medical or emergency personnel from working with patients exposed to high levels of radiation. Irradiated patients do not become radioactive. 

The exciting radiation irradiates a conical volume of the sample. The Raman radiation emerging from this volume irradiates optimally the beam splitter of the interferometer through the circular Jacquinot aperture. 

External radiation (irradiation) because radioactive material is not deposited on or in the body, decontamination is not necessary... 

Ionizing radiation provides enough energy to eject electrons from atoms or molecules. The absorption characteristics and primary ionization reactions are therefore mainly dependent on the overall composition and density of the irradiated material. Figure 2.3A schematically depicts the most important events in polymers induced by ionizing radiation. Irradiation may first lead to excitation or ionization within the molecules [2]. In addition to other reaction and relaxation paths, excited molecules may dissociate into two free radicals, whereas the ionized molecules preferentially dissociate into a free radical and a radical ion. 

According to studies of the photooxidation and radiation irradiation of low-molecular amines and polyamides [38, 95, 96], the most labile hydrogen atom is situated at the carbon atom next to the NH- group. 

C1 Chapiro, A. Chemical Nature of the Reactive Species Produced in Polymers by Ionizing Radiations. Irradiation of Polymers. Advances in Chemistry Series 66, Ch. 2, ACS Washington D.C., 1967. 

The half-value dose is the dose at which a property has been reduced to one half of its original value. Electron accelerators of various designs or y-radiation sources based on radioactive cobalt 60 ( Co) are the radiation sources typically used for targeted electron irradiation. The changes in plastics caused by radiation are the same for all types of radiation. Irradiation does not turn plastics radioactive. The only exceptions are neutrons (that occur almost exclusively in the core of nuclear reactors). They can activate plastics. 

The infrared beam emerging from the interferometer of an FT-IR spectrometer enters a polarizer, a PEM, and then an accessory for reflection-absorption measurement. The plane of polarization of the infrared beam after passing through the polarizer may be either parallel or perpendicular to the sample stage of the accessory for reflection-absorption measurement, and the pressure axis of the PEM is oriented at 45° to the plane of polarization of the entering infrared beam. When pressure is applied to the PEM at frequencythe polarized infrared beam is modulated by the PEM, and its polarization is switched at frequency 2/jjj between that parallel to the plane of incidence on the surface of the sample and that perpendicular to the same plane. As noted previously, it is necessary to set/ , greater than the maximum value of the modulation frequency 2t v produced by the interferometer. When a beam of polarized infrared radiation irradiates a thin film on a metal substrate... 

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