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B. Lendl, J. Hayden, J.P. Waclawek:
"Fabry-Pérot Photothermal Interferometry (FP-PTI) for trace gas sensing in small sample volumes";
Vortrag: SciX 2017, Reno, Nevada (eingeladen); 08.10.2017 - 13.10.2017.

Advances in Analytical Chemistry are often linked to technological developments in neighboring disciplines. This also concerns the recent development of quantum cascade lasers, which allows realization of sensing approaches in the mid-IR range that are different and more powerful compared to classical absorption measurements based on Lambert-Beer law. This presentation will focus on trace gas sensing using Photothermal Interferometry (PTI) on the example of sulfur dioxide. In PTI modulated absorption of the analyte produces a modulated change in the refractive index of the sample gas due to sample heating. The proposed set-up uses the cavity of a NIR Fabry Pérot (FP) interferometer as gas cell. The gas sample is excited using a distributed feedback Quantum Cascade Laser operated in the 2f-WM mode. The change in the refractive index of the sample produces a change in the transmission curve of the FP interferometer which is probed using a NIR laser. A new optical layout for rugged FP-PTI will be presented for the first time. This geometry efficiently assures long term operational stability along with single digit ppb sensitivities in a gas volume of just a few cubic millimeters.

http://publik.tuwien.ac.at/files/publik_266515.pdf