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

Volume

15

Issue

11

fYear

2015

Firstpage

6141

Lastpage

6146

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;

fLanguage

English

Journal_Title

Sensors Journal, IEEE

Publisher

ieee

ISSN

1530-437X

Type

jour

DOI

10.1109/JSEN.2015.2453271

Filename

7152834