Investigation of NLO Properties of Eriochrome Black T Colloidal Solution: Role of Surfactant and Reverse Micelles

The photophysical and nonlinear optical properties of Eriochrome Black T (EBT) in micelles, with two charge types of surfactant and reverse micelles (RMs) in a wide range of sizes, were investigated via ultraviolet–visible absorption, fluorescence spectroscopy, and a Z-scan technique. Accordingly, a significant redshift in absorbance and fluorescence quenching of the EBT was observed with an increase in cetyltrimethylammonium bromide (CTAB) concentration. Comparably, the nonlinear absorption coefficient ( β ) of the EBT decreased following an increase in cationic CTAB concentration, due to an increasing trend in the CTAB:EBT complex in the solution, and it decreased following an increase in anionic aerosol OT concentration. The same behavior was further detected for the nonlinear index of refraction ( n 2 ). The β value of the EBT also decreased with an increase in the size and concentration of the RMs, while the n 2 was enhanced.