Ionization high-energy electrons

Mass spectrometry is not based on absorption of electromagnetic radia tion but monitors what happens when a substance is ionized by collision with a high energy electron... 

Polybutene can be cross-linked by irradiation at ambient temperature with y-rays or high energy electrons in the absence of air. The performance of articles manufactured from polybutene is only slightly affected by ionizing radiation at doses below 30 kGy (3 Mrad) (26). PMP is also relatively stable to P-and y-radiation employed in the sterilization of medical suppHes (27). 

Electron ionization An ionization method employed in mass spectrometry in which analytes, in the vapour phase, are bombarded with high-energy electrons. 

From a chemist s viewpoint, the most important act of ionizing radiation (usually X-rays, y-rays or high energy electrons) is electron ejection. Initially the ejected electrons have sufficient energy to eject further electrons on interaction with other molecules, but the electrons ultimately become thermalised and then are able to interact "chemically". We consider first various reaction pathways for these electrons, and then consider the fate of the "hole" centres created by electron ejection. [We refer to electron-gain and electron-loss centres rather than to radical-anions and -cations since, of course, the substrate may comprise ions rather than neutral molecules. 

Electrostatic repulsion between high-energy electrons -produced from an accelerator, or by photon interaction with substrate atoms - and valency electrons in the polymer cause excitation and ionization. The chemical reactions result from these species. 

DEPTH PROFILE. The secondary electrons produced by ionization processes from an incident beam of high-energy electrons are randomly directed in space. Spatial "equilibrium" is achieved only after a minimum distance from the surface of a polymer in contact with a vacuum or gaseous environment (of much lower density). Consequently, the absorbed radiation dose increases to a maximum at a distance from the surface (2 mm for 1 MeV electrons) which depends on the energy of the electrons. The energy deposition then decreases towards zero at a limiting penetration depth. 

Auger electron spectroscopy spect The energy analysis of Auger electrons produced when an excited atom relaxes by a radiationless process after ionization by a high-energy electron, ion, or x-ray beam. Abbreviated AES. o zha i lek.tran spek tras-ko pe ... 

It should be noted that a Maxwellian form of fie) is a reasonable approximation to the actual distribution at low electron energies. This observation is indicated in Figure 5 i24). However, the first ionization potential of most atoms and molecules is above eV. Thus, many of the important homogeneous processes that occur in glow discharges, such as ionization, take place as a result of high energy electrons in the "tail" of the distribution. These electrons are precisely the ones that are not adequately described by a Maxwellian distribution function. 

X-rays, or gamma rays generated by nuclear decay. Ionizing radiation also includes several types of subatomic particles, such as beta radiation (high-energy electrons) and alpha radiation (helium ions) and others. Medical X-rays are an example of a common beneficial exposure to ionizing radiation. Nuclear radiation is used to generate electricity and cure disease, but is also an important element in military weapons. Uses of nuclear radiation pose serious issues of human exposure and environmental contamination. 

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