Proof of concept for use of two-colour fibre laser technology for detection of multiple atmospheric species by laser-induced fluorescence spectroscopy

Lead Research Organisation: University of Leeds
Department Name: Sch of Chemistry

Abstract

In this proposal we aim to exploit novel fibre laser technology developed by NovaWave Technologies (Redwood City, CA) for integration into the Leeds FAGE (fluorescence assay by gas expansion) instrument for the field measurement of HCHO radicals and NO2 using laser-induced fluorescence (LIF) spectroscopy. The prototype laser technology already exists for excitation of HCHO at 353nm, and following incorporation into the FAGE instrument we project a sensitivity of 50 ppt in 1 sec using this laser. The capabilities of the fibre laser technology will be extended by employing tunable radiation at ca. 530 nm from the laser to detect NO2 via by LIF spectroscopy. Performance and reliability of the fibre laser will be much better in difficult environments, for example aircraft cabins. We intend to collaborate closely with the group of Frank Keutsch (University of Wisconsin) who has experience of using these lasers for LIF measurements in the field. Formaldehyde (HCHO) is the simplest and one of the most abundant of carbonyl species, being emitted directly and generated from the OH initiated oxidation of biogenic and anthropogenic VOCs. The photolysis of HCHO and its reaction with OH leads to the formation of HO2, which in the presence of NOx leads to tropospheric ozone formation, which is a climate gas and harmful to humans and plants at high concentrations. The relatively long lifetime of HCHO means that transport processes influence its budget, making it very difficult to calculate using photochemical models based on situ chemistry, and direct measurements are essential. Although several methods exist for the measurement of HCHO, agreement between techniques has often been poor, and datasets for HCHO are not extensive, particularly in the UK, severely limiting the exploitation of radical data measured during collaborative field campaigns. The fibre based LIF instrument would enable sensitive measurements with good temporal resolution to be made on ground and aircraft platforms.

Publications

10 25 50
 
Description HCHO has been measured with the new instrument developed in this award in several field campaigns:
York (2014)
Weybourne (2015)
Beijing (2016, 2017)
Now deployed on the BAe146 FAAM aircraft, and has measured HCHO during the MOYA, Zwamps and ACSIS 4 campaigns
Exploitation Route Aircraft measurements using this instrument are planned following fitting in 2018 - and this has now occurred in Jan/Feb 2019
Sectors Environment

 
Description NCAS Capital Equipment
Amount £25,000 (GBP)
Organisation Natural Environment Research Council 
Sector Public
Country United Kingdom
Start 01/2017 
End 01/2019
 
Title Aircraft measurements of HCHO on the FAAM BAe 146 
Description The instrument developed during this award has now been operated aboard the BAe146 FAAM aircraft to measure atmospheric formaldehyde levels. 
Type Of Material Improvements to research infrastructure 
Year Produced 2019 
Provided To Others? Yes  
Impact HCHO measurements are now available to the atmospheric measurement community from the BAe 146 FAAM aircraft 
 
Description Invited Seminar (CalTech) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact Invited Seminar at the California Institute of Technology, Pasadena, California. I included the results from AIRPRO in my talk.
Year(s) Of Engagement Activity 2018