AQUEOUS DISSOLVED-GAS MEASUREMENTS USING NEAR-INFRARED RAMAN-SPECTROSCOPY

Near-infrared Raman spectra of several gases dissolved in an aqueous m edium have been acquired and analyzed for the first time. Spectra of d issolved and gaseous CO2, SO2, N2O, dimethyl ether, and O-2 are presen ted and compared. Raman-forbidden bands in the spectrum of gaseous dim ethyl ether are observed in the dissolved spectrum; this result can be explained by relaxed selection rules due to lowered symmetry. Raman s cattering enhancements in the dissolved phase are measured and shown t o compare well with a theoretical prediction accounting for internal f ield enhancements in water. Dissolved CO2 is measured quantitatively a t concentrations from 0 to 250 Torr with the use of the method of part ial least-squares, with an average prediction error of 12 Torr.