Optimal conditions and measuring functionals in the measurements of diffusion coefficients

Abstract

In tracer diffusion experiments, the linear dependence of the measured intensity with time is useful as an approximation after a certain induction time. We have shown here that by choosing suitable initial conditions and counting efficiency, the linear plot applies from the commencement of the experiment.

A study using non-radioactive methods to determine the concentration of the diffusing substance has also been made. The concept of a measuring functional, which may be linear or non-linear with respect to the concentration, has been used. In such cases after a set time the logarithm of the measured quantity follows a straight line with respect to time, and the first eigenvalue which includes the diffusion coefficient can be obtained from the slope. Harned and Nuttal's conductance method is an example of the use of a non-linear functional to determine the diffusion coefficient.