%0 Journal Article
%T THz QCL-Based Cryogen-Free Spectrometer for in Situ Trace Gas Sensing
%A Luigi Consolino
%A Saverio Bartalini
%A Harvey E. Beere
%A David A. Ritchie
%A Miriam Serena Vitiello
%A Paolo De Natale
%J Sensors
%D 2013
%I MDPI AG
%R 10.3390/s130303331
%X 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 ¡Ö 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.
%K terahertz spectroscopy
%K quantum cascade lasers
%K trace gas sensing
%U http://www.mdpi.com/1424-8220/13/3/3331