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Electron fast-moving

Nuclei have many times more mass than electrons. Diiringa very small period of tim e wh en th e mo vein en t of heavy nuclei is n egli-gible, electrons are moving so fast that their distribution is smooth. Th is leads to the approximation that the elec iron distri-biition IS dependent only on the fixed positions of nuclei and not on their velocities. This approximaiion allows two simplifications... [Pg.11]

Ionizing collision. An ion/neutral reaction in which an electron or electrons are stripped from the ion and/or the neutral species in the collision. Generally, this term describes collisions of fast-moving ions or atoms with a neutral species in which the neutral species is ionized. Care should be taken to emphasize if charge stripping of the ion has taken place. [Pg.444]

In the bacterial reaction center the photons are absorbed by the special pair of chlorophyll molecules on the periplasmic side of the membrane (see Figure 12.14). Spectroscopic measurements have shown that when a photon is absorbed by the special pair of chlorophylls, an electron is moved from the special pair to one of the pheophytin molecules. The close association and the parallel orientation of the chlorophyll ring systems in the special pair facilitates the excitation of an electron so that it is easily released. This process is very fast it occurs within 2 picoseconds. From the pheophytin the electron moves to a molecule of quinone, Qa, in a slower process that takes about 200 picoseconds. The electron then passes through the protein, to the second quinone molecule, Qb. This is a comparatively slow process, taking about 100 microseconds. [Pg.239]

A cathode ray consisting of fast-moving electrons flows through the spark coil and into the partially evacuated tube... [Pg.27]

In a cathode ray tube, fast-moving electrons excite the gas, causing a giow between the eiectrodes. [Pg.6]

The Moseley equation, v = A(Z -B)2, where v is the frequency of the emitted X-ray radiation, Z is the atomic number and A and B are constants, relates the frequency of emitted X-rays to the nuclear charge for the atoms that make up the target of the cathode ray tube. X-rays are emitted by the element after one of its K-level electrons has been knocked out of the atom by collision with a fast moving electron. In this question, we have been asked to determine the values for the constants A and B. The simplest way to find these values is to plot Vv vs. Z. This plot provides Va as the slope and - Va (B) as the y -intercept. Starting with v = A(Z-B)2, we first take the square root of both sides. This affords Vv = Va (Z - B). Multiplying out this expression gives Vv = Va (Z)... [Pg.192]

An essential ingredient in the innovation history in the area of chemicals is, however, doubtless the development of recipes for preparations and their specific adaptation to the requirements of fast-moving manufacturing processes, for example in the automotive, electronics, printing and paper industries. This occurs mainly on the basis of the existing inventory of primary materials. [Pg.37]

Fig. 3.6. Synchrotron radiation. A fast-moving electron is forced to spiral along the line of force of a magnetic held and emits non-thermal radiation in the direction of motion of the particle. This type of radiation is confined to a narrow cone whose axis coincides with the direction of motion. Fig. 3.6. Synchrotron radiation. A fast-moving electron is forced to spiral along the line of force of a magnetic held and emits non-thermal radiation in the direction of motion of the particle. This type of radiation is confined to a narrow cone whose axis coincides with the direction of motion.
Fast-moving electrons, for their part, spiral through magnetic fields emitting... [Pg.120]

This chapter is about molecules. A molecule is a collection of nuclei Z., Z/,... at rest (in the Bom-Oppenheimer approximation) in a sea of fast-moving electrons. The nuclei can be identified and thus provide convenient reference marks. Each nucleus found in the molecule, say, Z], can be viewed as the nucleus of a giant atom extending over the entire molecule is surrounded by charges, just as in an ordinary atom, with the difference that motionless positive point charges are now part of its environment. Of course, the electronic content is still described by its stationary density. [Pg.35]

A practical application of the wave properties of fast-moving electrons is the electron microscope, which focuses not visible-light waves but rather electron waves. Because electron waves are much shorter than visible-light waves, electron microscopes are able to show far greater detail than optical microscopes, as Figure 5.15 shows. [Pg.155]

X-rays generated by sudden stoppage of fast-moving electrons. [Pg.1406]

P Decay is named for the second most ionizing rays that were found to emanate from uranium samples. The naturally occurring p rays were identified as fast moving (negative) electrons relatively easily, but it took many years to obtain a full understanding of the emission process. The difficulty lies in the fact that two particles are... [Pg.199]

Another mechanism for electron energy loss in matter is the emission of Cerenkov radiation. When a beam of fast moving charged particles with a velocity... [Pg.517]


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