Electronic absorption and fluorescence spectra were recorded for aqueous solns. of SDS and N,N'-dimethylthiacyanine iodide (DMTC) over a wide concentration range. Mol. aggregate states were characterized by SDS-dependent change of spectral feature with the aid of the M. Kasha et al., (1985) mol. exciton theory. The surfactant-dye salt was formed and condensed in a highly aggregate state below the cmc of 2, and was dissolved after the formation of 2 micelles.

Key words: AQUEOUS SOLUTION, SURFACTANTS, SPECTROGRAPHIC ANALYSIS, SODIUM SULFATE, C12 COMPOUNDS, FLUOROSPECTROPHOTOMETRY, CYANINE DYES