Activation energy defined

This equation results from the assumption that the actual reaction step in themial reaction systems can happen only in molecules (or collision pairs) with an energy exceeding some tlireshold energy Eq which is close, in general, to the Arrhenius activation energy defined by equation (A3.13.3). Radiative energization is at the basis of classical photochemistry (see e.g. [4, 3 and 7] and chapter B2.5) and historically has had an interesting sideline in the radiation... 

Here, A zp is the zero-point energy corrected activation energy defined in Eq. (6.22). At intermediate temperatures, Eq. (6.24) smoothly connects these two limiting cases. In many examples that do not involve H atoms, the difference between the classical and zero-point corrected results is small enough to be unimportant. 

Figure 1.33. Kinetics of o-xylene hydrogenation The apparent activation energy defined as...

Figure 8.9. Activation energy defined over temperatures — 40°C to 25°C for the P3MT films redoped with various chemical species of dopant as a fimction of the dopant concentration. Reprinted with permission from Reference 35. Copyright 1985 Elsevier Science S. A.

Thus, according to the transition-state method, the activation energy defined by the Arrhenius expression is, strictly speaking, not constant and slightly dependent on temperature. However, this effect is so small that it can scarcely be measured. 

For several reactions, the rate data is sufficiently accurate and extensive to show clearly that the Arrhenius activation energy, defined by Eact = —d nkld IRT), is, itself, a temperature-dependent quantity. ... 

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