Bremen 2017 – scientific programme

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UP: Fachverband Umweltphysik

UP 5: Postersession

UP 5.11: Poster

Tuesday, March 14, 2017, 16:40–18:10, GW2 B3010

LED Based Quarz Enhanced Photoacoustic Spectroscopy: A cost effective solution for in-situ detection of volcanic Sulfur Dioxide? — •Lukas Tirpitz, Simone Wald, Nicole Bobrowski, Ulrich Platt und Jonas Kuhn — Institut für Umweltphysik Heidelberg

Volcanic gas measurements, particularly of sulfur dioxide (SO2) play an essential role for the examination of volcanic degassing processes. In the field application, in-situ instruments are frequently affected by harsh environmental conditions and the high corrosivity of volcanic gas species, making such measurements laborious, expensive, and frequently unreliable. Sensors for volcanic SO2 based on quartz enhanced photoacoustic spectroscopy (QEPAS) use the fact, that SO2 is the dominant absorber of UV-radiation around 300 nm wavelength. Thus the amount of radiation absorbed by the sample gas depends only on its SO2 content. Since the absorbed radiation is converted to heat, illumination by a pulsed light source causes the temperature and thus pressure of the sample gas to oscillate and to emit an acoustic wave. A small resonant 32.8 kHz quartz tuning fork (as it is used in any quartz clock) serves as a microphone to detect the signal intensity and to determine the SO2 concentration. Typically, large and expensive laser systems are used as light sources. We are developing a cost effective, mobile, and potentially ultra-compact QEPAS instrument using commercially available UV light emitting diodes, which we expect to be sufficient to reliably detect typical volcanic plume SO2 abundances at useful detection limits (<1 ppm).