Neutralization—reionization experiments with a cell containing potassium vapour

The design, operation and performance of a potassium vapour cell for exothermic neutralization—reionization (NR) experiments using a VG-ZAB-2F mass spectrometer is described. With the new cell it is possible to maintain over a long period of time a sufficiently high and very stable vapour pressure and this enables the acquisition of many noise-free exothermic NR spectra as single scans. Also with the new cell there is no or minimal leakage of the metal vapour to other parts of the mass spectrometer. Features of selected NR mass spectra are discussed. Not only does exothermic neutralization permit the study of highly excited molecules but the method can also be used to differentiate among isomeric ions where other methods fail.