title: Parts-per-trillion-level detection of nitrogen dioxide by cantilever-enhanced photo-acoustic spectroscopy.
abstract: We present a simple and highly sensitive cantilever-enhanced photo-acoustic sensor for detection of nitrogen dioxide. A noise equivalent detection limit of 50 parts-per-trillion in 1 s is demonstrated. The limit was reached with an average optical power of 4.7 W using a continuous-wave laser at 532 nm. The achieved normalized noise equivalent absorption coefficient was 2.6×10(-10)  W cm(-1) Hz(-1/2).
authors.forename: Jari
authors.initials: J
authors.lastname: Peltola
authors.forename: Tuomas
authors.initials: T
authors.lastname: Hieta
authors.forename: Markku
authors.initials: M
authors.lastname: Vainio