High-energy beams

Figure 5.1. Processes occurring when a high-energy beam of electrons interacts with a thin specimen. The arrows do not necessarily represent the physical direction of the signal, but indicate the region in which it...

Greene, Moursund, and Ross). Scattering, Elastic, of High-Energy Beams Repulsive 10 135... 

Chemical reaction that is induced by ionizing radiation with y-ray. X-ray, electron, or other high-energy beams. 

The fast atom bombardment ionization (FAB) technique is a soft ionization method, typically requiring the use of a direct insertion probe for sample introduction in which a high energy beam of Xe atoms, Cs+ ions, or massive glycerol-NH4+ clusters sputter the sample and matrix from the probe surface (Figure 8). 

High-energy beams involving the above particles are created in particle accelerators, in which a charged particle is drawn forward by an electro-sfafic field wifh a charge opposite that of the particle (like charges repel one another, opposites attract) as the particle passes the source of each field, the charge of fhe field is reversed so that the particle is now pushed onto another field source. 

The compound of interest is dissolved in a high-boiling viscous solvent such as glycerol a drop is placed on a thin metal sheet, and the compound is ionized by the high-energy beam of xenon atoms (Xe). Ionization by translational energy minimizes the amount of vibrational excitation, and this results in less destruction of the ionized molecules. The polar solvent promotes ionization and allows diffusion of fresh sample to the surface. Thus ions are produced over a period of 20-30 min, in contrast to a few seconds for ions produced from solid samples. 

Elastic Scattering of High-Energy Beams Repulsive Forces (Amdur ... 

Extremely thin, self-supporting film electrodes have been successfully produced. For example, polypyrrole films of 120 nm thickness have been used successfully to grow microcrystallites, followed by removal of the film plus crystallites from the substrate for characterization of the crystallographic structure and orientation of the microcrystallites by transmission electron microscopy with selected area electron diffraction [23]. Thin-film electrodes have been applied to allow transmission of high-energy beams, including x-rays, for in situ... 

Probably the most important of these is the diffraction of waves from the film. X-ray diffraction, neutron diffraction and electron diffraction have all been employed and examples of their use will be discussed below. For films less than a few micrometres thick, X-rays and neutrons can only be used in the low angle mode as the diffracting power of such films is not sufficient to obtain useful results if the incident beam is directed normally at the film. Electron diffraction can be used with relatively thin films but the destructive effect of the high energy beam often damages the film before an image can be recorded. 

Mass spectrometry is used to measure the molecular mass of a compound and provides a method to obtain the molecular formula. It differs from the other instrumental techniques presented thus far because it does not involve the interaction of electromagnetic radiation with the compound. Instead, molecules of the compound being studied are bombarded with a high-energy beam of electrons in the vapor phase. When an electron from the beam impacts on a molecule of the sample, it knocks an electron out of the molecule. The product, called the molecular ion (represented as A/f), has the same mass as the original molecule but has one less electron. It has both an odd number of... 

East atom bombardment (EAB) On applying a high-energy beam of argon (or zenon) to a biomolecule, it becomes volatile and ionizes. 

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