Raman studies in micellar sodium octyl sulphate solutions

Abstract

Raman spectra of micelle-forming sodium octyl sulphate have been measured as a function of concentration over the critical micelle concentration. Accurately measured frequency shifts of the C—H stretching region and relative intensities at 1080 and 3125 cm^–1 characteristic of gauche isomeric forms can be used as indicators of micelle formation. Quantitative Raman measurements can be used to measure solubilization of organic additives to micellar solutions. Studies of the effects of cations on the halfwidth of the O—SO^–₃ symmetric stretching vibration indicate a strong interaction with Ca²⁺, perhaps even complex formation. This blocking effect may account for the decreased catalytic ability of micelles in the presence of Ca²⁺.