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W. Ritter, H. Moser, J.P. Waclawek, J. Ofner, C. Reidl-Leuthner, A. Genner, B. Lendl:
"MidIR Quantum Cascade Lasers: New opportunites for process analytical chemistry";
Vortrag: EuroPact 2014, Barcelona; 06.05.2014 - 09.05.2014.

QCLs as an enabling technology for improved gas monitoring, liquid sensing and near field mid-IR imaging

Mid-IR quantum cascade lasers (QCLs) hold promise to revolutionize the way mid-IR spectroscopy is employed in process analytical chemistry. Due to their highly attractive properties which include high spectral power densities (>100mW/cm-1), small size (e.g. TO8), room temperature operation and recently also increased tunability, a range of new measurement concepts can be envisioned and realized.
At the Vienna University of Technology we have investigated and tested the spectroscopic properties and resulting capabilities of QCLs for different industrial applications. For the analysis of liquids our spin-off company QuantaRed Technologies has successfully defined a new standard (ASTM D 7678-11) for the measurement of oil-in-water, which meanwhile is used in more than 20 countries. In the field of gas analysis on-going research activities are carried out in co-operation with the Austrian Chemical Industry with the aim to develop prototypes for rapid and sensitive detection of several analytes by in-line (NO, NO2) or on-line measurements (e.g. H2S, CS2) for process monitoring and for assuring work-place safety.
In this presentation we plan to review the current state of the art of Quantum Cascade Lasers technology including their spectroscopic properties as revealed by step-scan FTIR spectroscopy (time res.: 2 ns, spectral res.: 0.1 cm-1). Furthermore, the working principle of the new oil-in-water method will be introduced and results obtained at challenging applications (oil-rigs) reported. Concerning in-line stack gas monitoring, results on simultaneous measurement of NO/NO2 will be presented and compared to standard extractive measurement technologies. Finally, quartz enhanced photo-acoustic spectroscopy with ppb sensitivities in small volumes (2 ml), as well as near field mid-IR imaging (spatial res.: ~50 nm) will be introduced.