title: Spectroscopic detection of biological NO with a quantum cascade laser.
abstract: Two configurations of a continuous wave quantum cascade distributed feedback laser-based gas sensor for the detection of NO at a parts per billion (ppb) concentration level, typical of biomedical applications, have been investigated. The laser was operated at liquid nitrogen temperature near lambda = 5.2 microns. In the first configuration, a 100 m optical path length multi-pass cell was employed to enhance the NO absorption. In the second configuration, a technique based on cavity-enhanced spectroscopy (CES) was utilized, with an effective path length of 670 m. Both sensors enabled simultaneous analysis of NO and CO2 concentrations in exhaled air. The minimum detectable NO concentration was found to be 3 ppb with a multi-pass cell and 16 ppb when using CES. The two techniques are compared, and potential future developments are discussed.
authors.affiliation: Rice Quantum Institute, Rice University, Houston, TX 77251-1892, USA. menzel@iap.uni-bonn.de
authors.forename: L
authors.initials: L
authors.lastname: Menzel
authors.forename: A A
authors.initials: AA
authors.lastname: Kosterev
authors.forename: R F
authors.initials: RF
authors.lastname: Curl
authors.forename: F K
authors.initials: FK
authors.lastname: Tittel
authors.forename: C
authors.initials: C
authors.lastname: Gmachl
authors.forename: F
authors.initials: F
authors.lastname: Capasso
authors.forename: D L
authors.initials: DL
authors.lastname: Sivco
authors.forename: J N
authors.initials: JN
authors.lastname: Baillargeon
authors.forename: A L
authors.initials: AL
authors.lastname: Hutchinson
authors.forename: A Y
authors.initials: AY
authors.lastname: Cho
authors.forename: W
authors.initials: W
authors.lastname: Urban
mesh_terms: D001944:Breath Tests / Q000295:instrumentation* / Q000379:methods; D002245:Carbon Dioxide / Q000032:analysis; D005069:Evaluation Studies as Topic; D007834:Lasers; D009569:Nitric Oxide / Q000032:analysis*; D011789:Quantum Theory; D013057:Spectrum Analysis; D014867:Water / Q000032:analysis
chemical_list: D014867:Water; D002245:Carbon Dioxide; D009569:Nitric Oxide