The determination of the distance dependence and electromagnetic enhancement of surface-enhanced Raman spectroscopy and the sorption of the chlorinated and nonchlorinated organic compounds to surfactant-modified montmorillonite

Surface enhanced Raman spectroscopy (SERS) consists of two enhancements: chemical and electromagnetic (EM). Knowing the SERS EM enhancement is useful in developing SERS sensors that involve analyte specific coatings. The results can also be used as a guide for designing future SERS sensors. Our method of measuring the EM enhancement involved self-assembled monolayers (SAMs) and adsorbed benzene and tert-butylbenzene. The SAMs were made with different lengths of n-alkanethiols and were used as variable thickness barriers to separate the EM from the chemical enhancement.; Experiments designed to study the sorption of common organic compounds onto organo-clays from aqueous solutions using Raman spectroscopy and gas chromatography were performed. The sorption was modeled as adsorption and absorption using a thermodynamic relationship. It was determined that the sorption more closely followed an absorption process. A similar technique was also used to study the absorption of chlorinated ethylenes onto organo-clays from aqueous solutions. A surfactant was designed specifically to target absorption of chlorinated ethylenes. The sorption properties of an organo-clay made with this chlorinated surfactant were compared to those of an organo-clay made with a nonchlorinated surfactant.