Researchers directly observed tetroxides for the first time, showing they exist in normal air conditions and play key roles in atmospheric chemistry, combustion, and medicine.
Scientists have, for the first time, directly detected an extremely short-lived molecule that has long been considered central to how oxidation works in everything from air pollution to human biology.
The breakthrough, reported in Science Advances, comes from a collaboration between researchers at KTH Royal Institute of Technology in Sweden and Kinetic Chemistry Research in California. They successfully observed oxygen-rich tetroxides, a class of molecules first proposed more than 70 years ago but never seen directly until now.
“This compound is the equivalent of the Higgs boson for oxidation chemistry,” says Barbara Nozière, professor of physical chemistry at KTH Royal Institute of Technology. “Its existence was assumed for decades but nobody had ever seen it.”
Decades-Old Theory Confirmed: The Russell Mechanism
Scientists first proposed tetroxides in the 1950s as part of the Russell mechanism, a reaction in which two unstable organic radicals briefly combine. This interaction produces a molecule containing four oxygen atoms linked together, but only for a fraction of a second.
Despite their short lifetimes, tetroxides are believed to play a central role in oxidation reactions, which drive combustion, influence air quality, and occur continuously inside living organisms. These reactions help break down pollutants in the atmosphere, but they can also generate harmful byproducts, including compounds that contribute to smog and tiny airborne particles.
Until now, evidence for these molecules was indirect, inconsistent, or based on experiments under extremely cold and controlled laboratory conditions. The researchers confirmed their presence using an advanced mass spectrometry method designed to detect highly unstable molecules without breaking them apart.
Breakthrough Detection Method Reveals Stability in Air
Unexpectedly, the team found that tetroxides are relatively stable in air, unlike results from earlier experimental conditions.
“The study confirms that tetroxides can exist at room temperature, in air, without needing extremely cold conditions used in earlier experiments,” Noziere says.
Implications for Atmosphere, Pollution, and Chemical Reactions
Finding tetroxides in both outdoor environments and living organisms suggests they may take part in previously unknown reaction pathways and produce new oxidation products that require further study.
This could affect how long pollutants, such as paint solvents or smoke, remain in the atmosphere, as well as how other airborne compounds and aerosol particles form.
Noziere adds that measuring their lifespan, between 0.2 and 200 milliseconds, helps scientists better understand the speed of these reactions and the range of products they can generate.
The discovery also has important implications for medical research, including studies of oxidative stress and cancer treatments, where the Russell mechanism is already being explored in new therapeutic strategies, she says.
Reference: “Observing elusive tetroxides in gas-phase radical reactions supports the Russell mechanism” by Barbara Nozière and Roger Patrick, 13 March 2026, Science Advances.
DOI: 10.1126/sciadv.aeb6495
The research was funded with a grant from the European Research Council.
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