difuosiokerros

Difuosiokerros, or diffusion layer, is a region adjacent to an interface where mass transport is governed primarily by diffusion, causing solute concentrations to change from interfacial values to those in the bulk solution. This concept is especially important at solid–liquid interfaces such as electrode surfaces, where chemical reactions create or consume species.

The diffusion layer forms when a reaction at the interface alters local concentrations and convection is insufficient to rapidly mix the solution. In a stagnant (quiescent) solution, the layer grows with time as δ ∝ sqrt(D t), where D is the diffusion coefficient and t is time. In systems with fluid flow or stirring, the layer is effectively kept at a thinner, steady thickness set by the balance between diffusion and convective transport.

The diffusion layer has practical significance in electrochemistry and related fields. It determines the limiting current in diffusion-controlled processes and affects reaction kinetics observed at an electrode. In transient experiments, currents follow i(t) ∝ t^(-1/2) as described by the Cottrell equation. For systems with controlled hydrodynamics, such as a rotating disk electrode, the diffusion layer thickness is influenced by rotation and is described by relationships like the Levich equation.

Difuosiokerros is relevant to electrodeposition, corrosion, and electroanalytical sensing, where mass transport limits or modulates reaction rates. Its characterization helps in understanding and predicting current responses, concentration profiles, and the efficiency of electrochemical processes. See also diffusion, diffusion boundary layer, Cottrell equation, and Levich equation.