Neutralization-reionization mass spectrometry

Abstract

The use of neutralization-reionization mass spectrometry for polyatomic species has grown rapidly in the last 3 years. Mass-selected positive or negative ions are charge exchanged to form fast neutrals of chosen internal energies. Energy can be added to the neutrals by collision or photoexcitation, the neutral products reionized to positive or negative ions, and mass-selected product ions structurally characterized by further collisional dissociation and mass analysis. The method has found broad applicability for ion structure characterization and analysis; the lower isomerization tendency of neutrals, vs. that of the corresponding ions, has been particularly useful for hydrocarbon ion characterization. Of probably the broadest interest is the method's ability to prepare unusual, unstable neutral species from stable ions and to characterize the unimolecular chemistry of these neutrals. Detailed energy surfaces have been reported for carbenes, ylides, diradicals, clusters, organometallics, and hypervalent, sterically strained, and anti-aromatic molecules.