Title :
Continuous Monitoring of Formaldehyde Photolysis Products by THz Spectroscopy
Author :
Omar, Abdelaziz ; Eliet, Sophie ; Cuisset, Arnaud ; Dhont, Guillaume ; Coeur-Tourneur, Cecile ; Bocquet, Robin ; Mouret, Gael ; Hindle, Francis
Author_Institution :
Lab. de Physico Chim. de l´Atmos., Univ. du Littoral Cote d´Opale, Dunkirk, France
Abstract :
A terahertz sensor system based on a commercially available multiplier chain operating in the range 600-900 GHz is used to monitor the photolysis of formaldehyde H2CO. The exposure of formaldehyde to solar radiation provokes dissociation via two pathways: 1) the molecular channel producing molecular carbon monoxide CO and 2) the radicalar channel giving formyl HCO. Monitoring the concentrations of CO and H2CO via pure rotational transitions, allowed us to obtain the kinetic rate constants for these two channels. In order to establish the detection limit of HCO, a modified spectrometer configuration employing the Zeeman modulation was used with acetaldehyde CH3CHO and photosensitization by mercury.
Keywords :
Zeeman effect; dissociation; organic compounds; photodissociation; reaction rate constants; spectrochemical analysis; terahertz spectroscopy; terahertz wave detectors; Zeeman modulation; acetaldehyde; dissociation; formaldehyde photolysis; formyl HCO; frequency 600 GHz to 900 GHz; kinetic rate constants; mercury photosensitization; molecular carbon monoxide; molecular channel; radicalar channel; solar radiation; spectrometer configuration; terahertz sensor system; terahertz spectroscopy; Absorption; Frequency modulation; Kinetic theory; Monitoring; Structural beams; Temperature measurement; THz frequency multiplication; THz time-resolved quantification; photolysis; trace gas detection;
Journal_Title :
Sensors Journal, IEEE
DOI :
10.1109/JSEN.2015.2453271
