Heidelberg 2015 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 46: Laser Applications: Laser Spectroscopy
Q 46.5: Vortrag
Mittwoch, 25. März 2015, 15:30–15:45, K/HS2
Investigation of metal capillaries for fluorescence reduction in a capillary Raman system for high-sensitivity gas analysis — •Hendrik Seitz-Moskaliuk1, Simone Rupp1, Timothy James1, Andreas Off1, and Helmut H. Telle2 — 1Institute of Technical Physics, Karlsruhe Institute of Technology, Germany — 2Instituto Pluridisciplinar, Universidad Complutense de Madrid, Spain
Raman spectroscopy is a widely used tool for analysing the composition of gas mixtures. It allows non-contact and inline multispecies gas measurements. A highly sensitive Raman system for detecting small amounts of gases can be realised by using a glass capillary with a silvered inner surface as the gas cell. The laser light is sent through the capillary which offers a long scattering region, while the highly reflective silvering makes it possible to collect a large fraction of the Raman-scattered light. Both the long scattering region and the effective Raman light collection lead to a high signal. A disadvantage of this approach, however, is the high fluorescence background. Fluorescence light is produced by laser light in glass, in this special case if the laser hits the capillary frontally or if laser light tunnels through the silvering into the glass.
This talk presents the results of a comparison experiment in which different metal tubes were used as Raman cell. Spectra of air were taken and compared to spectra obtained with a glass capillary. It could be shown that the metal capillaries reach the same signal-to-noise ratios as the glass capillary. Further improvements are suggested to even exceed the glass capillary performance.