A photoacoustic trace-gas sensor for the measurement of nitric oxide with a detection limit of 500 parts in 10^9 has been demonstrated. The radiation source was a thermoelectrically cooled distributed-feedback quantum-cascade laser operating in pulsed mode near 5.3 µm with an average laser power of 8 mW. A resonant photoacoustic cell was excited in its first longitudinal mode by the modulated laser light. Preliminary measurements have been performed to test the performance of our photoacoustic sensor; possible improvements to reach lower detection limits are discussed.
© 2005 Optical Society of America
Angela Elia, Pietro Mario Lugarà, and Corrado Giancaspro, "Photoacoustic detection of nitric oxide by use of a quantum-cascade laser," Opt. Lett. 30, 988-990 (2005)