The ''Foil-Mesh'' method for measuring mean lifetimes of long-lived molecular ions

Abstract A method for measuring the mean lifetime of molecular ions undergoing unimolecular dissociation is presented. It can be used to measure molecular ions even if the beam has a large impurity fraction in it, as demonstrated by a measurement of the mean lifetime of 4 He 20 Ne 2+ . Furthermore, this method is not limited to mean lifetimes comparable to the flight time of the ions through the experimental setup as other commonly used methods. It can be used to measure mean lifetimes up to about two orders of magnitude longer than the flight time, as demonstrated using 12 CD 2 2+ and 3 He 40 Ar 2+ as examples.