Spectral properties of rhodamine 6G in smectite dispersions: Effect of the monovalent cations

► Spectral properties of R6G in the dispersion of montmorillonite, saturated with various monovalent cations depend on the type of the cations. ► Adsorption of the dye cations is a very fast process. ► R6G molecular aggregates formed in montmorillonite colloidal systems bear both the features of H- and J-aggregates. ► Significant effects of the properties of inorganic ions and swelling properties montmorillonite on R6G molecular aggregation were observed.