title: Difference-frequency-based tunable absorption spectrometer for detection of atmospheric formaldehyde.
abstract: High-sensitivity detection of formaldehyde (CH2O) at 3.5315 micrometers (2831.64 cm-1) is reported with a diode-laser-pumped, fiber-coupled, periodically poled LiNbO3 spectroscopic source. This source replaced the Pb-salt diode laser Dewar assembly of an existing tunable diode-laser absorption spectrometer designed for ultrasensitive detection of CH2O. Spectra are recorded with 2f-modulation spectroscopy and zero-air rapid background subtraction. Initial measurements reported here, determined from multiple measurements of a flowing 7.7 parts per billion by volume (ppbv, parts in 10(9)) CH2O in air mixture, indicate replicate precisions as low as 0.24 ppbv.
authors.affiliation: Electrical and Computer Engineering Department, Rice University, Houston, Texas 77005, USA.
authors.forename: D G
authors.initials: DG
authors.lastname: Lancaster
authors.forename: A
authors.initials: A
authors.lastname: Fried
authors.forename: B
authors.initials: B
authors.lastname: Wert
authors.forename: B
authors.initials: B
authors.lastname: Henry
authors.forename: F K
authors.initials: FK
authors.lastname: Tittel
mesh_terms: D001272:Atmosphere / Q000737:chemistry*; D004784:Environmental Monitoring / Q000295:instrumentation*; D004867:Equipment Design; D005069:Evaluation Studies as Topic; D005557:Formaldehyde / Q000032:analysis*; D007834:Lasers; D007854:Lead; D013055:Spectrophotometry, Infrared / Q000295:instrumentation*
chemical_list: D005557:Formaldehyde; D007854:Lead