Results 261 to 270 of about 224,627 (303)

Kinetics of graphitization—II. Pre-exponential factors

Carbon, 1969
Abstract In the preceding article on kinetics of graphitization it has been demonstrated that for three typical cokes used industrially, the activation energy for graphitization is the same and is equal to 230 ± 15 kcals/mol. However, in contrast to work done elsewhere, it is shown that systematic differences in respective rates of graphitization of ...
H.N. Murty, D.L. Biederman, E.A. Heintz
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The impact of overpotential on the enthalpy of activation and pre-exponential factor of electrochemical redox reactions

Physical Chemistry Chemical Physics, 2022
The energetics of the electrochemical, electro-inhibiting and electrocatalytic reactions as a function of overpotential.
Anand Kumar Tripathi, Divya Priyadarshani, Miji E Joy, Rajan Maurya, Manoj Neergat   +4 more
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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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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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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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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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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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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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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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