title: Photoacoustic measurement of methane concentrations with a compact pulsed optical parametric oscillator.
abstract: A pulsed periodically poled lithium niobate optical parametric oscillator operating in a cavity with a grazing-incidence grating configuration was used for sensitive and precise measurement of trace quantities of methane in nitrogen by photoacoustic spectroscopy with a novel differential photoacoustic detector. A sensitivity of 1.2 parts in 10(9) by volume of methane was obtained in direct calibration measurements (not extrapolated). With this apparatus, in situ measurement of the methane concentration in ambient air under atmospheric conditions was demonstrated.
authors.affiliation: Institute of Physical Chemistry, University of Heidelberg, Germany.
authors.forename: András
authors.initials: A
authors.lastname: Miklós
authors.forename: Chin-How
authors.initials: CH
authors.lastname: Lim
authors.forename: Wei-Wei
authors.initials: WW
authors.lastname: Hsiang
authors.forename: Geng-Chiau
authors.initials: GC
authors.lastname: Liang
authors.forename: A H
authors.initials: AH
authors.lastname: Kung
authors.forename: Andreas
authors.initials: A
authors.lastname: Schmohl
authors.forename: Peter
authors.initials: P
authors.lastname: Hess