Abstract: We report on a set of high-sensitivity terahertz spectroscopy experiments making use of QCLs to detect rotational molecular transitions in the far-infrared. We demonstrate that using a compact and transportable cryogen-free setup, based on a quantum cascade laser in a closed-cycle Stirling cryostat, and pyroelectric detectors, a considerable improvement in sensitivity can be obtained by implementing a wavelength modulation spectroscopy technique. Indeed, we show that the sensitivity of methanol vapour detection can be improved by a factor ≈ 4 with respect to standard direct absorption approaches, offering perspectives for high sensitivity detection of a number of chemical compounds across the far-infrared spectral range.
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Consolino, L.; Bartalini, S.; Beere, H.E.; Ritchie, D.A.; Vitiello, M.S.; De Natale, P. THz QCL-Based Cryogen-Free Spectrometer for in Situ Trace Gas Sensing. Sensors 2013, 13, 3331-3340.
Consolino L, Bartalini S, Beere HE, Ritchie DA, Vitiello MS, De Natale P. THz QCL-Based Cryogen-Free Spectrometer for in Situ Trace Gas Sensing. Sensors. 2013; 13(3):3331-3340.
Consolino, Luigi; Bartalini, Saverio; Beere, Harvey E.; Ritchie, David A.; Vitiello, Miriam S.; De Natale, Paolo. 2013. "THz QCL-Based Cryogen-Free Spectrometer for in Situ Trace Gas Sensing." Sensors 13, no. 3: 3331-3340.