What is it about?
This study explores what happens when two types of charged particles, CO+ (a positively charged carbon monoxide molecule) and O- (a negatively charged oxygen atom), meet and neutralize each other. The reaction, called mutual neutralization, is important in many cool plasmas where such molecular ions are present, e.g. in planetary atmospheres and cometary coma. However, until very recently, scientists were unable to determine exactly what products are formed or how the reaction unfolds. Using the unique DESIREE facility in Stockholm, Sweden, researchers were to identify exactly what products were formed, how much energy was released in the process, and thus unravel the molecular dynamics driving the interaction.
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Why is it important?
This research reveals the detailed outcomes of an important reaction in space chemistry. It shows that when CO+ and O- meet and neutralize they mostly (in 69% of the cases) form an excited CO molecule (but never a ground-state CO molecule) and an oxygen atom, but sometimes (the remaining 31%) the CO molecule breaks apart. In the former case, the excited CO molecule will later release its extra energy as light, mostly in the ultraviolet range, but also in visible and infrared light. The latter outcome only forms ground-state atoms and does not lead directly to any photon emission. The findings show that, unlike similar mutual neutralization reactions of O- with other molecules like NO+ and O2+, CO+ doesn't always break apart when neutralized, and this is most likely due to the fact that CO has a much stronger molecular bond. The results will help scientists better model environments such as planetary atmospheres and cometary tails where these ions are common.
Perspectives
The unique cryogenic double electrostatic ion-ring experiment, DESIREE, in Stockholm, Sweden is a facility having a huge scientific impact with studies into the mutual neutralization of molecular ions. Cutting edge detectors and data analysis techniques allow deep insights into the dynamics driving these complex interactions, with applications to planetary atmospheres, interstellar clouds, and technical plasmas. We hope the paper inspires readers to consider whether there are questions in your area of research in which colliding oppositely charged molecular ions might provide a valuable new perspective.
Richard Thomas
Stockholm University
Read the Original
This page is a summary of: Disentangling dissociative and nondissociative reaction dynamics in molecular mutual neutralization reactions between CO
+
and O
−, Proceedings of the National Academy of Sciences, July 2026, Proceedings of the National Academy of Sciences,
DOI: 10.1073/pnas.2603388123.
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