Abstract

Fiber optics were used to interface a Raman spectrometer to a long (1 m) sample tube, with the objective being increased sensitivity. Internal reflection of the laser light and the Raman scatter within the sample tube permitted a long solution length to be sampled, increasing the Raman sensitivity by factors of 30-50 over conventional capillary tube sampling systems. In addition, the sample was subjected to much lower power densities than with systems employing a focused beam, thus minimizing radiation damage. Detection limits of 10⁻⁹ to 10⁻⁸ M were achieved for resonance Raman scatterers, and normal Raman scatterers could be detected at the 1 × 10⁻⁵ M level.

Long fiber-optic remote Raman probe for detection and identification of weak scatterers

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An Optical Cell for Long Pathlengths at Low Temperatures

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