In a new study, published in Environmental Science: Atmospheres, scientists have used neutron reflection to examine pollutants taken from three different environments: urban, Antarctic, and wood burning materials. They were able to measure how these materials react with the hydroxyl radical OH—one of the most reactive molecules found in the atmosphere.
[...] Professor Martin King from Royal Holloway's Department of Earth Sciences, said: "Our work clearly demonstrates that to understand coating of atmospheric aerosols we must use real samples extracted from the atmosphere rather than only pure compounds from a chemist's shelf as simulants because their behavior is different and not representative."
[...] "This makes it easier to study them and possible to understand the detailed mechanisms at work, so remains an important approach to enhance our understanding of key atmospheric processes. However, this work should be complemented by studies of real samples collected from a diverse set of locations."
The process for collecting and testing "real" samples has been carefully designed by the researchers. The material is collected in situ on quartz filters which allows the particles to attach and form a film specific to distinct environments across the globe. This product is then rinsed into a solution, transported to a neutron facility, where the solution is evaporated to reveal the film.
Inside the neutron facility, neutrons are reflected from the film to follow its reaction with the OH radicals to ultimately establish how rapidly these films would break down on atmospheric particles.
Rosalie H. Shepherd, Martin D. King, Adrian R. Rennie, et al. Measurement of gas-phase OH radical oxidation and film thickness of organic films at the air–water interface using material extracted from urban, remote and wood smoke aerosol [open], Environmental Science: Atmospheres (DOI: 10.1039/D2EA00013J)