When Opposites Fatally Attract: The Mutual Neutralisation Story
One reaction involving atomic and molecular ions which is extremely difficult to measure and explore in detail is mutual neutralisation, where a positive ion and a negative ion meet up, and neutralise. Thanks to a unique ion storage ring device, DESIREE, in Stockholm Sweden, these oppositely charged ions can be stored and controlled, then merged together in a cryogenically cold environment where the MN reaction happens. Using a cutting edge camera, we identify the reaction products and reconstruct the moment these opposites became fatally attracted, and neutralised.
From a hundred km and higher in the Earth’s upper atmosphere, the reactions of simple atomic and molecular ions give rise to atmospheric escape, a hot geocorona, as well as lighting up the night sky with red, green, blue, and ultra-violet skyglows. The mutual neutralisation of these simple ions is a key but poorly understood reaction. For the first time, in the mutual neutralisation between the key NO+ and O- ions, we determine that the reaction completely destroys the molecule, releasing energy into the atomic fragments which heats up the atmosphere but does not lead to a colourful skyglow. We demonstrate the power of DESIREE to answer questions relevant to a range of plasma environments where mutual neutralisation of molecular ions is a key but poorly understood reaction.
More information
Mutual neutralization of NO$^+$ with O$^-$ Physical Review Letters
Last updated: January 18, 2024
Source: Fysikum