Neutralization Agents for Neutralization-Reionization Mass Spectrometry

摘要

Vaporized metals provide the most efficient targets for charge-exchange neutralization of fast ions; with Mercury or Sodium at least 25% of the 10 keV acetone enoi ions can be converted into collectable neutrals. These targets are superior for measuring neutralization (NR) mass spectra, producing 5 times the abundance of neutrals from acetone ions as acetone itself, for which resonant charge exchange is possible, or as xenon, in comtrast to a recent recommendation. Metal vapor targets produce approximately an order of magnitude more neutrals by charge exchange than by collisionally activated dissociation, while the proportions are reversed with helium as the target. Targets such as Na of much lower ionization energy produce neutrals of higher internal energy, which can fragment differently than the original ions, providing additional structural information. Experimental procedures are detailed for producing routine NR mass spectra, for which mercury is a particularly convenient target.