什么是diffusion limited reaction?

什么是diffusion limited reaction?
什么是diffusion limited reaction?

什么是diffusion limited reaction?
Diffusion-controlled (or diffusion-limited) reactions are reactions that occur so quickly that the reaction rate is the rate of transport of the reactants through the reaction medium (usually a solution).[1] As quickly as the reactants encounter each other,they react.The process of chemical reaction can be considered as involving the diffusion of reactants until they encounter each other in the right stoichiometry and form an activated complex which can form the product species.The observed rate of chemical reactions is,generally speaking,the rate of the slowest or "rate determining" step.In diffusion controlled reactions the formation of products from the activated complex is much faster than the diffusion of reactants and thus the rate is governed by diffusion.
Diffusion control is rare in the gas phase,where rates of diffusion of molecules are generally very high.Diffusion control is more likely in solution where diffusion of reactants is slower due to the greater number of collisions with solvent molecules.Reactions where the activated complex forms easily and the products form rapidly are most likely to be limited by diffusion control.Examples are those involving catalysis and enzymatic reactions.Heterogeneous reactions where reactants are in different phases are also candidates for diffusion control.
One classical test for diffusion control is to observe whether the rate of reaction is affected by stirring or agitation; if so then the reaction is almost certainly diffusion controlled under those conditions.
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蚀刻的机制，按发生顺序可概分为「反应物接近表面」、「表面氧化」、「表面反应」、「生成物离开表面」等过程。所以整个蚀刻，包含反应物接近、生成物离开的扩散效应，以及化学反应两部份。整个蚀刻的时间，等于是扩散与化学反应两部份所费时间的总和。二者之中孰者费时较长，整个蚀刻之快慢也卡在该者，故有所谓「reaction limited」与「diffusion limited」两类蚀刻之分...

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蚀刻的机制，按发生顺序可概分为「反应物接近表面」、「表面氧化」、「表面反应」、「生成物离开表面」等过程。所以整个蚀刻，包含反应物接近、生成物离开的扩散效应，以及化学反应两部份。整个蚀刻的时间，等于是扩散与化学反应两部份所费时间的总和。二者之中孰者费时较长，整个蚀刻之快慢也卡在该者，故有所谓「reaction limited」与「diffusion limited」两类蚀刻之分

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有限扩散反应