Studies of the gas-phase reactivity of molecular doubly-charged ions.
Molecular Physics seminar
Monday 27 October 2008
to 11:00 at
Stephen D. Price (Chemistry Department, University College London)
There is increasing interest in the role of molecular dications (doubly-charged molecules) in both astrochemistry and the chemistry of planetary ionospheres. Small molecular dications, such as N22+, are highly-rich metastable species with lifetimes to dissociation ranging from femtoseconds to many seconds. This talk will discuss the consequences of the bimolecular interactions of molecular dications with other atoms and molecules.
Recent laboratory developments have shown that molecular dications possess a rich and unusual bimolecular chemistry. As well as the expected electron-transfer reactivity, molecular dications exhibit extensive bond-forming reactivity in low-energy collisions with neutral molecules. These “chemical” reactions usually generate pairs of product monocations, often accompanied by neutral species:
N22+ + C2H2 -> N+ + NC2H+ + H
The product monocations from these reactions possess considerable translational energies and may subsequently have markedly different reactivity to that of thermalised monocations. The reaction dynamics of these unusual reactions can now be investigated by multi-parameter coincidence experiments and reveal unusual reaction pathways, involving often involving initial complexation with the neutral species:
N22+ + O2 -> [N2O2]2+ -> N2O2+ + O
N2O2+ -> N2+ + O+