The diffusion of reaction products from a radioactive monolayer
The one-dimensional diffusion equation has been solved for transfer at an exponentially decaying rate from an area source into a semi-infinite diffusion medium. Numerical values of the concentration distribution are given for a wide range of the values of the parameters. The solutions have been used to calculate the radioactive counting rate of a diffusing radioactive substance which is being released from the surface, assuming exponential absorption of radiation by the medium. The results have been used specifically to calculate the true rate of exchange of radio-iodine between a monomolecular layer of α-iodostearic acid and iodide ion in a water substrate from the measured rate of decay of radioactivity measured at the surface, but have other possible applications.