Electron harpooning in reactions of sodium cluster ions with nitrous oxide

The collisional reaction of Nan+ (2 </ n ⩽ 9) with N2O was investigated by using a tandem mass spectrometer equipped with four octopole ion guides. Oxide ions, NakO+, and intact ions, NAp+ (p < n), were found to be produced from the reaction of Nan+ with N2O. The collision-energy dependence of the absolute cross section for each product channel was measured at collision energies up to 5 eV in the center-of-mass frame. The cross section for the production of NakO+ decreased with increasing collision energy, while that for the production of Nap+ increased. This observation is interpreted as that electron harpooning from Nan2 to N2O preludes NakO+ formation. The collision-energy dependence of the partial cross section for the production of Nap+ is explained by a hard sphere collision model employed in the explanation of the collisional dissociation of Nan2 by rate-gast impact.