Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Probability of electronically

Molecular ions have an important role in charge carrier losses in the ionosphere. The probability of electron-atom-... [Pg.2809]

The wave function T is a function of the electron and nuclear positions. As the name implies, this is the description of an electron as a wave. This is a probabilistic description of electron behavior. As such, it can describe the probability of electrons being in certain locations, but it cannot predict exactly where electrons are located. The wave function is also called a probability amplitude because it is the square of the wave function that yields probabilities. This is the only rigorously correct meaning of a wave function. In order to obtain a physically relevant solution of the Schrodinger equation, the wave function must be continuous, single-valued, normalizable, and antisymmetric with respect to the interchange of electrons. [Pg.10]

Any alteration in AG will thus affect the rate of the reaction. If AG is increased, the reaction rate will decrease. At equilibrium, the cathodic and anodic activation energies are equal (AG 0 = AG 0) and the probability of electron transfer is the... [Pg.16]

The physical picture of the transition is different here from that for nonadiabatic reaction. Equation (34.34) shows that the probability of electron transfer becomes equal to 1 when the acceptor energy level passes a small energy interval Ae 1/(2jiYlzP) near the Fermi level. However, unUke the nonadiabatic case,... [Pg.652]

Figure 1.7 Schematics of simultaneous incoming probability of electrons and photons for (a) continuous mode and (b) pulsed mode. Figure 1.7 Schematics of simultaneous incoming probability of electrons and photons for (a) continuous mode and (b) pulsed mode.
The rate of electron accumulation at ionized traps in the depletion zone of the Schottky barrier in the Au/ZnO contact is in proportion to the concentration of unoccupied traps, frequency of metal parti-cle/metastable atom interaction events, and to the probability of electron capture per a trap in a single event of interaction between metastable atoms and metal particle. [Pg.336]

The high-energy electrons generated in the plasma mainly initiate the chemical reactions by reactions with the background gas molecules (see Table 12.1). Direct electron impact reactions with NO are usually not important for NO decomposition, as in real flue gas, as well as in experiments in simulated gas, the concentrations of NO are very low (some hundreds of ppm), and therefore, the probability of electron collisions is also low. [Pg.376]

This is termed an independent electron model, and terms such as i j (.(1 ) are termed molecular orbitals (MOs). This equation is equivalent to assuming that the probabilities of electrons occupying the same region of space are independent, i.e., that each electron moves in the averaged field of the bare nuclei and the other (N— 1) electrons. [Pg.14]

If an external field is present, the procedure would be the same except that now in place of 0(i) and (n) one would use the corresponding probabilities of electron escape as given by the Onsager equation in the presence of an external field (see Sect. 9.5). [Pg.299]

Molecular mechanics force fields rest on four fundamental principles. The first principle is derived from the Bom-Oppenheimer approximation. Electrons have much lower mass than nuclei and move at much greater velocity. The velocity is sufficiently different that the nuclei can be considered stationary on a relative scale. In effect, the electronic and nuclear motions are uncoupled, and they can be treated separately. Unlike quantum mechanics, which is involved in determining the probability of electron distribution, molecular mechanics focuses instead on the location of the nuclei. Based on both theory and experiment, a set of equations are used to account for the electronic-nuclear attraction, nuclear-nuclear repulsion, and covalent bonding. Electrons are not directly taken into account, but they are considered indirectly or implicitly through the use of potential energy equations. This approach creates a mathematical model of molecular structures which is intuitively clear and readily available for fast computations. The set of equations and constants is defined as the force... [Pg.39]

This is called a chemical, radical or stepwise mechanism. Or was it (ii) by the action of the bridging group to increase the probability of electron transfer by tunneling, termed resonance transfer 56,9i... [Pg.280]

As mentioned in Section 3.4, clusters of metal atoms of varying sizes can be prepared. The presence of alkali atom clusters in the vapour phase is well documented. Such clusters have a much lower ionization energy than that of an isolated atom and also have a high electron affinity. The probability of electron transfer is therefore considerably greater in a metal cluster. It is indeed known in the case of caesium that as the density of caesium increases (from isolated atoms in a low-density gas to a liquid), larger clusters form and charge-transfer becomes increasingly favoured as the density... [Pg.351]

The key requirement for a SET step in the photocatalytic process seems to be the surface complexation of the substrate, according to an exponential dependence of the probability of electronic tunneling from the distance between the two redox centers [66]. However, as was pointed out in the preceding section on the key role of back reactions, the presence of a SET mechanism could be a disadvantage from an applicative point of view. If the formed SET intermediate (e.g., a radical cation) strongly adsorbs and/or does not transform irreversibly [e.g., by loss of CO from a carboxylic acid or fast reaction with other species (e.g., superoxide or oxygen)], it can act as a recombination center, lowering the overall photon efficiency of the photocatalytic process. [Pg.223]

Not only has the escape probability of electron—cation pairs in hydrocarbon liquids been widely studied, but also, in semiconductors, the electron—hole pair created by photo-excitation of an electron behaves very similarly and has been similarly analysed [330, 331]. [Pg.184]

Returning to equation (38), in the limit that ve vn, Ke = 1 and vet = vn. Electron transfer reactions that fall into this domain where the probability of electron transfer is unity in the intersection region have been called adiabatic by Marcus. Reactions for which Kei < 1, have been called non-adiabatic . In the limit that ve 2vn and e = vjvn, the pre-exponential term for electron transfer is given by vet = ve. This was the limit assumed in the quantum mechanical treatment using time dependent perturbation theory. [Pg.347]

W2 is then proportional to the probability of electron 1 being found at position x1 and electron 2 at xz. The significant points to be noted are (1) that if = x2 the wave function vanishes so that the configuration has zero probability and (2) that there are two equivalent most probable configurations in which the electrons are in different halves of the wire. These two configurations differ only in the numbering of the electrons and are otherwise indistinguishable. [Pg.183]

The probability of the atom ionization per unit of time is in proportion with the probability of electron transfer through the barrier created by the potential (5). Most probable is tunneling along the direction of the field so, to a first approximation, one-dimensional rather than three-dimensional considerations can be used (see Fig. 3)... [Pg.13]


See other pages where Probability of electronically is mentioned: [Pg.165]    [Pg.643]    [Pg.650]    [Pg.86]    [Pg.36]    [Pg.280]    [Pg.27]    [Pg.351]    [Pg.135]    [Pg.125]    [Pg.474]    [Pg.122]    [Pg.263]    [Pg.51]    [Pg.440]    [Pg.158]    [Pg.151]    [Pg.474]    [Pg.65]    [Pg.347]    [Pg.356]    [Pg.239]    [Pg.123]    [Pg.531]    [Pg.544]    [Pg.174]    [Pg.292]    [Pg.212]    [Pg.248]    [Pg.308]    [Pg.356]    [Pg.180]   


SEARCH



Probabilities of Electronically Adiabatic Processes

Probabilities of Electronically Non-Adiabatic Processes

Probability density, of electron

Probability distribution, of electrons

Probability electron

Probability electronic

Probability of electron transfer

Probability of electronic transition

Probability of finding an electron

Probability, of finding electrons

The Probability of Electron Tunneling

© 2024 chempedia.info