Heidelberg 2015 – scientific programme
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Q: Fachverband Quantenoptik und Photonik
Q 62: Poster: Quantum Optics and Photonics III
Q 62.86: Poster
Thursday, March 26, 2015, 17:00–19:00, C/Foyer
Improvements of a capillary Raman system for high-sensitivity gas analysis — •Simone Rupp1, Timothy M. James1, Andreas Off1, Hendrik Seitz-Moskaliuk1, and Helmut H. Telle2 — 1Institute of Technical Physics, Karlsruhe Institute of Technology, Germany — 2Instituto Pluridisciplinar, Universidad Complutense de Madrid, Spain
Raman spectroscopy is an advantageous tool for the compositional analysis of gases: inline, non-contact, non-destructive and allowing to detect multiple species at once. Conventional 90° Raman systems have been set up by our group and were successfully developed towards a high precision and sensitivity. However, in order to enable real-time applications, e.g. in process control, or the detection of trace amounts of gases at sub-mbar total pressures, it is necessary to further increase the sensitivity beyond that of the conventional technique. One promising approach is the use of a highly-reflective, hollow capillary as the gas cell. The elongated scattering volume and the large light collection angle vastly enhance the Raman signal compared to conventional setups. However, current implementations suffer from a high fluorescence background due to interactions between laser light and glass from optical components. The resulting shot-noise limits the achievable sensitivity. We have investigated methods to minimize the fluorescence background in the setup whilst maximizing the collected Raman signal. This poster discusses these methods and shows that the resulting sensitivity enhancement goes along with other advantages like a higher mechanical stability or the possibility to use higher laser powers.