Reaction and Diffusion
A set number of molecules is released at one side of a cell-like space and must diffuse to find a target on the other side. Change the particle type or its diffusion coefficient and watch how molecular size changes the search process. The reaction happens when a diffusing particle reaches the target region.
Current particle size
1.0 nm
Captured fraction
0.00
First capture time
—
Mean arrival time
—
Diffusive time scale L²/4D
1.50 s
Cell, Source, Diffusing Particles, and Target
Capture Fraction in Time
Arrival-Time Distribution
Main ideas
Diffusion is a random walk, with a typical displacement that grows like the square root of time. Larger or more hindered molecules usually have smaller diffusion coefficients, so they explore space more slowly.
Here the reaction is encounter-limited. A particle is counted as reacted when it diffuses into the target region.