Metastable ions by photoion—photoelectron coincidence PIPECO

1 Metastable ions by photoion—photoelectron coincidence (PIPECO) 

Lifetimes of reactant ions in the range 1—100ps can be determined in PIPECO studies from asymmetric time-of-flight distributions. Ions with these lifetimes decompose during acceleration [908] and hence the translational energy of these fragment ions so formed is less than that of fragment ions formed before acceleration. 

In these rather special PIPECO experiments, ions are being produced with selected internal energy and their lifetimes are measured. FIK achieves measurement of time, and PIPECO in its usual form and charge exchange fix energy. To both preselect energy and measure time is the desired, yet rare, level of experiment in mass spectrometry. 

The only reservation about these determinations of lifetimes by PIPECO might concern their accuracy. The analysis of the asymmetric time-of-flight distribution constitutes, in essence, an analysis of peak 

There are disagreements between certain results obtained by PIPECO on metastable ions and the results for the same decompositions obtained in PIPECO experiments, which vary the source residence time [717, 718] (see Sect. 5). The origin of these conflicting results has, however, yet to be agreed upon. 

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