The Ephemeral project could be turning point in understanding the atmosphere’s chemistry

“These radicals are difficult to observe directly. They have never been observed individually in the atmosphere and very few groups in the world are able to detect them directly in the laboratory. We are developing a new technique for the direct observation of these radicals, which can be used in the real atmosphere. Since the beginning of the project we have studied about 20 different organic radicals in the laboratory, some of them being observed for the first time ever,” says Barbara Nozière.

In her lab at KTH, Barbara Nozière is talking excitedly about her research and the Ephemeral project, surrounded by reactors and instruments dedicated to detecting organic radicals. Some she built herself and brought with her from her last job at Centre National de la Recherche Scientifique in France, but there are also new Time-of-Flight Mass Spectrometer (TOF-MS) instruments being modified to be able to detect radicals.

“One main objective of the project is to detect the organic radicals in the real atmosphere with these new instruments. The performances that we have achieved with them is already sufficient to perform unique laboratory investigations, such as the first study of the uptake and reactions of the radicals with surfaces, published a few months ago. Interactions between organic radicals and surfaces, for instance with aerosols and cloud droplets in the atmosphere, are expected to be ubiquitous. Yet they have never been studied because of the challenge of detecting these radicals. Our project is currently making some major advances on these aspects,” says Barbara Nozière.

Air quality and climate

The Ephemeral project has run half its time and according to Barbara, the research group is half way towards completing the main goal. But why is it so important to understand how organic radicals work? Barbara Nozière explains that organic radicals determine the composition of most chemical systems in contact with oxygen and involving organic compounds: the Earth’s atmosphere, surface natural waters (lakes, oceans), but also combustion systems (fires, engines, furnaces), and aerobic living organisms (i.e. those that breathe oxygen).

“In the atmosphere, these radicals determine how organic compounds are being oxidized, what kind of compounds they produce and how much before they get to CO2. That is important for air quality, ozone formation, smog chemistry, and climate,” Barbara Nozière says.

“Over the last ten years, also it has been discovered that these radical reactions not only control the gas-phase composition of the atmosphere but can also build aerosols, which is also important for air quality and climate. Studying these reactions producing condensable compounds and, ultimately, aerosols, is another important direction of research on which we are currently very active and that will greatly benefit from our project.”

Understanding the atmosphere’s chemistry

The reason for the project to receive an Advanced Grant from the ERC is that detecting volatile organic radicals in the atmosphere will expand the ability to study atmospheric radical chemistry from the current 1-dimensional observations (sum of the concentration of all organic radicals), to multi-dimensional observations (the concentrations of the many individual radicals). This would be a major turning point in understanding the oxidative cycles in atmosphere’s chemistry.

Beyond the ERC Advanced project and the atmosphere, Barbara Nozière would also like to collaborate with other fields of chemistry on these radicals, such as combustion or biochemistry and medicine. The same organic radicals that she is studying in the atmosphere are also involved in biological processes such as oxidative stress or lipid peroxidation, which are responsible for many medical problems such as cardiovascular diseases, cancer and aging.

“The detection technique that we are developing is much more sensitive and selective than Electron Paramagnetic Resonance (EPR) or Electron Spin Resonance (ESR) spectroscopies, which are used to study these radicals in biochemistry today. I am thus convinced that our expertise on the detection of these radicals could led to some significant progress in these fields of research as well,” says Barbara Nozière.

Text and photo: Jon Lindhe

Organic radicals

Organic radicals are organic molecules with one single electron on their outer shell. Unlike stable molecules, this electron makes them very reactive to combine with other molecules or radicals and produce some stable molecules. Thus most radicals only have short lifetimes (also called reaction intermediates), which makes them difficult to observe.