Determination of the size and charge of dye aggregates in aqueous electrolyte solution

The stability of two dyes in the presence of electrolyte has been investigated over the period required for measurement of diffusion coefficients in glass sinter diaphragm cells, and the results indicate that particle sizes remain constant over such times. The effect of concentration differences within the cell during a run has been measured and was found to give rise to considerable error. Corrected diffusion coefficients have been used together with electrophoretic mobilities to calculate aggregation numbers and the extent of counter- ion uptake into the aggregates. The results are shown to be consistent with the ?stack of coins? model for dye aggregation.