CAN HIGH-PRESSURE RAMAN-SPECTROSCOPY BE SIMPLIFIED - A MICROSCALE OPTICAL-FIBER CAPILLARY CELL FOR THE STUDY OF SUPERCRITICAL FLUIDS

This paper reports the design of a simple and inexpensive optical fibe r capillary flow cell which is ideally suited to Raman spectroscopy an d, in particular, the analysis of high-pressure supercritical fluid so lutions. Light is delivered directly to the solution by use of optical fibers which run along the bore of the capillary. For maximum efficie ncy of light collection, the capillary is mounted directly onto and al ong the axis of the entrance slit of a dispersive Raman spectrometer. The Raman spectra of supercritical carbon dioxide (scCO2) solutions of gases (e.g., nitrogen and hydrogen), and solid solutes (e.g., naphtha lene) are presented.