Results 231 to 240 of about 105,813 (262)

Theoretical Pre-Exponential Rate Factors for Abstraction Reactions

The Journal of Chemical Physics, 1959
Equations have been derived for the pre-exponential rate factors of abstraction reactions. The activated complex is considered as made up of three rigid groups. Classical partition functions are used and it is shown that the use of classical methods gives a simple expression which requires only a knowledge of several force-constants and bond lengths ...
Oktay Sinanoglu, Kenneth S. Pitzer
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Theoretical Pre-Exponential Factors for Twelve Bimolecular Reactions

The Journal of Chemical Physics, 1956
The Arrhenius pre-exponential factor A has been calculated and compared with experiment for a group of twelve bimolecular gas phase reactions of simple inorganic molecules. The most detailed form of the activated complex theory, a cruder method of hydrocarbon analogy, and the simple collision theory were used. Necessary assumptions about the properties
Dudley R. Herschbach, Harold S. Johnston, K. S. Pitzer, R. E. Powell   +3 more
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On the Pre‐Exponential Factor in the Rate Equation for Plastic Flow

physica status solidi (b), 1973
AbstractAlthough it is not generally possible to calculate the pre‐exponential factor ϵ0 directly from experimental results, the assumption that the obstacle‐dislocation interaction has the same temperature dependence as the shear modulus permits ϵ0 to be determined from the available data. An iterative procedure is described which, when convergent, is
T. Sueek, M. J. Luton, J. J. Jonas
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The pre-exponential factor in the conductivity of liquid semiconductors

Philosophical Magazine B, 1985
Abstract Consideration is given to certain liquids undergoing a metal-insulator transition with change of volume or composition. In the semiconducting phase a conductivity of the form σ =σ0 exp(- E/kT) is observed, and it is assumed that electrons move at a mobility edge. The value of the pre-exponential factor a.
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The pre-exponential factor in the conductivity of amorphous silicon

Philosophical Magazine B, 1985
Abstract The pre-exponential factor σ0 in the conductivity of a-Si:H, together with the mobility μext at the mobility edge (E c) are discussed. On the assumption (Mott 1984) that σ0 = 0·03 e 2/hL i, where L i is the inelastic diffusion length, and using experimental values of the time between collisions, it is found that σ0 = 16 Ω+1 cm+1 and μext = 8 ...
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The pre-exponential factor in activated reorientational processes

Chemical Physics Letters, 1969
Abstract Different approaches to the pre-exponential factor for processes in which a rotator crosses a potential barrier by thermal fluctuations are complexed. It is shown that Eyring's treatment, in its classical limit, is equivalent to that of Bauer and, furthermore, that Eyring's entropy of activation has no intrinsic qualitative significance. For
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Pre-exponential factor in the conductivity of liquid and amorphous semiconductors

Journal of Non-Crystalline Solids, 1985
Abstract It is suggested that the pre-exponential factor σ in the conductivity of non-crystalline systems should be 0.03 e 2 h L i , where Li is the inelastic diffusion length. Applications are suggested to hydrogenated amorphous silicon, to materials where small polarons are formed, to liquid semiconductors and to granular metal ...
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The pre-exponential factor of the escape probability in thermally stimulated processes

Applied Physics A Solids and Surfaces, 1987
The pre-exponential factor of the transition probability of a trapped charge carrier into an excited state is evaluated from two different approaches. The semi-classical treatment based on a thermodynamical concept involves the calculation of the vibrational entropy change from the partition sum.
M. B�hm, A. Scharmann
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Pre-exponential factor of the hopping conductivity in disordered carbon films

Bulletin of the Lebedev Physics Institute, 2010
The conductivity of carbon films grown by polymethylphenylsiloxane vapor decomposition in stimulated dc discharge plasma was studied. It is found that the Mott hopping conductivity \( \sigma \left( T \right) = \sigma _0 \left( T \right)\exp \left\{ { - \frac{{T_0 }} {T}^{{1 \mathord{\left/ {\vphantom {1 4}} \right.
E. A. Kataeva, A. D. Bozhko, S. V. Demishev   +2 more
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Energy gap and pre‐exponential factor in dark conduction by organic semiconductors

Journal of Polymer Science Part C: Polymer Symposia, 1967
AbstractThe values of Δε and σ0 in the expression σ = σ0 exp {−Δε/2kT} for the dark conductivity σ, tend to increase together over the whole range of organic semiconductors. They fall into a broad band of values confined roughly between two lines given by log σ0 = αΔε + β, the compensation rule, with log σ0 varying from 5 ± 4 for Δε equal to 1.0 e.v ...
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