Selective fragmentation and ionization of organic compounds using an energy-tunable rare-gas metastable beam source

Abstract

The initial use of an energy-tunable rare-gas metastable beam source generated by a corona discharge as an ionization source for mass spectrometry is reported. The metastable atom beam is produced external to theion source and its excitation energy is controlled by the rare gas which is employed. The metastable beam source can be used routinely and provides sensitivities of the same order as those obtained by electron impact. Preliminary results involving the analysis of aromatic and aliphatic compounds with four different rare-gas metastable atom beams (krypton, argon, neon and helium) are presented in order to show the tunable fragmentation and selective ionization capabilities of the metastable source. Thus, this source can be used to gain fundamental information on the physical properties of polyatomic molecules as well as the Penning ionization process itself, and for analytical-type applications such as those encountered in LC-MS and desorption-ionization. Overall, the results presented support the potential of the metastable beam source as a new tool for a wide range of mass spectral experiments.