A pulsed photoacoustic system for the spectroscopy and monitoring of hydrocarbon liquids using stimulated Raman scattering in a silica fibre as a near-infrared source

Raman scattering in an optical fibre has been utilized as the near-infrared source for a pulsed photoacoustic spectroscopic study of liquid hydrocarbo ns. An open-cell system is described and the performance criteria for pract ical photoacoustic instrumentation are discussed. Results show that a typic al signal-to-noise ratio of 50 may be achieved, which makes this system sui table for the detection of small concentrations of hydrocarbons in liquids. The photoacoustic system has been used to measure concentrations both of d issolved and of dispersed hydrocarbons and the results of this study indica te the practical potential for novel open-cell photoacoustic instrumentatio n for the detection of crude oil in water using near-infrared wavelengths i n a spectral region for which suitable diode losers are available.