Abstract: Photofading behaviors of four water-soluble symmetrical squarylium indocyanine dyes with various substituents at N atom in aqueous solution containing different surfactants such as cetyltrimethylammonium bromide(CTAB), sodium dodecyl sulfate(SDS) and Triton X-100(TX-100) were investigated, respectively. The results showed that the effect of surfactants on photofading behaviors of dyes follows an order of CTAB＞TX-100＞SDS. The dye with carboxyl group was affected most dramatically. At low concentration of CTAB, photofading degree of the dyes was increased with increasing concentration of CTAB. With the formation of micelles, photofading degree of the dyes was reduced with increasing concentration of CTAB.

Key words: cyanine dye, squarylium dye, surfactant, photofading behavior