A compact absorption spectrometer with a midinfrared tunable quantum cascade laser operating at 4.86μm (2054 cm <sup>-1</sup>) is used to measure lower concentrations of carbonyl sulfide (COS) in air. A detection sensitivity of ~30 parts in 10<sup>9</sup> of COS and the selectivity of two stable isotopes, <sup>12</sup>C<sup>16</sup>O<sup>32</sup>S and <sup>12</sup>C <sup>16</sup>O<sup>34</sup>S, are demonstrated. Specifically, the feasibility of detecting COS in expired human breath as a potential noninvasive medical diagnostic tool is investigated.
© 2003 Optical Society of America
(000.1430) General : Biology and medicine
(140.3070) Lasers and laser optics : Infrared and far-infrared lasers
(300.1030) Spectroscopy : Absorption
(300.6340) Spectroscopy : Spectroscopy, infrared
Chad Roller, Anatoliy A. Kosterev, Frank K. Tittel, Kiyoji Uehara, Claire Gmachl, and Deborah L. Sivco, "Carbonyl sulfide detection with a thermoelectrically cooled midinfrared quantum cascade laser," Opt. Lett. 28, 2052-2054 (2003)