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Activation energy

About: Activation energy is a(n) research topic. Over the lifetime, 22089 publication(s) have been published within this topic receiving 468017 citation(s). The topic is also known as: molar activation energy & Arrhenius activation energy.
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Journal ArticleDOI
01 Jul 1962-Vacuum
Abstract: Methods for determining the activation energy, rate constant and order of reaction from “flash-filament” desorption experiments are examined. Two heating schedules are considered: (a) a linear variation of sample temperature with time (T = T0+st), and (b) a reciprocal temperature variation ( 1 T = 1 T 0 −αt) . The activation energy of desorption is estimated from the temperature (Tp) at which the desorption rate is a maximum (for first-order reactions) and from the change of Tp with surface coverage (for second-order reactions). The order of the reaction is determined from the shape of the desorption rate versus time curve, or the variation of Tp with coverage. Applications of these methods to experiments on chemisorption and the desorption of ionically trapped gases are discussed. The effect of finite pumping speed in the system is analysed and the necessary corrections derived.

3,098 citations


Journal ArticleDOI
Abstract: A technique was devised for obtaining rate laws and kinetic parameters which describe the thermal degradation of plastics from TGA data. The method is based on the inter-comparison of experiments which were performed at different linear rates of heating. By this method it is possible to determine the activation energy of certain professes without knowing the form of the kinetic equation. This technique was applied to fiberglass-reinforced CTL 91-LD phenolic resin, where the rate law - (1/we)(dw/dt) = 1018e−55,000/RT [(w - wf)/w0,]5, nr.−1, was found to apply to a major part of the degradation. The equation was successfully tested by several techniques, including a comparison with constant temperature data that were available in the literature. The activation energy was thought to be correct within 10 kcal.

2,571 citations



Journal ArticleDOI
Abstract: Two methods of obtaining kinetic parameters from derivative thermoanalytical curves are proposed The methods are based on the general form of kinetic formulae and are applicable to general types of reactions governed by a single activation energy One method utilizes the linear relation between peak temperature and heating rate in order to estimate the activation energy, and only the information of the rate of conversion versus the temperature is necessary The other method needs the information of both the conversion and the rate of conversion versus the temperature, and the Arrhenius plot is made for an assumed kinetic mechanism

1,870 citations


Journal ArticleDOI
Abstract: A method is presented for determining activation free energies in complex molecular systems. The method relies on knowledge of the minimum energy path and bases the activation free energy calculation on moving along this path from a minimum to a saddle point. Use is made of a local reaction coordinate which describes the advance of the reaction in each segment of the minimum energy path. The activation free energy is formulated as a sum of two terms. The first is due to the change in the local reaction coordinate between the endpoints of each segment of the path. The second is due to the change in direction of the minimum energy path between consecutive segments. Both contributions can be obtained by molecular dynamics simulations with a constraint on the local reaction coordinate. The method is illustrated by applying it to a model potential and to the C7eq to C7ax transition in the alanine dipeptide. It is found that the term due to the change of direction in the reaction path can make a substantial contribution to the activation free energy.

1,089 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202222
2021554
2020541
2019545
2018606
2017629

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Topic's top 5 most impactful authors

T.P. Sinha

26 papers, 644 citations

Yanghuan Zhang

21 papers, 108 citations

Gabor A. Somorjai

16 papers, 1.1K citations

Sergey Vyazovkin

15 papers, 691 citations

Neeraj Mehta

14 papers, 87 citations