Search

We report the results of an experimental study of electron ionization of large helium nanodroplets doped with formic acid (FA). Several homologous series of cluster anions are observed, including [FA n -H] - , undissociated FA n - , and these ions complexed with one or more H 2 O. Some major features resemble those observed upon sputtering of frozen FA films but they differ significantly from results obtained by electron attachment to bare FA clusters in the gas phase. The FA n - and (H 2 O)[FA n -H] - series show abrupt onsets above n = 2 and 5, respectively. A prominent resonance in the anion yield occurs at 22.5 eV due to the formation of an intermediate He -* . Also observed are homologous series of [FA-H] - or [FA 2 -H] - complexed with helium. The cation chemistry is dominated by the production of protonated formic acid clusters, [FA n H] + , but various other homologous cluster ion series are observed as well. Graphical Abstract.

Mass spectroscopic investigations on tetrahydrofuran (THF, C 4 H 8 O), a common model molecule of the DNA-backbone, have been carried out. We irradiated isolated THF and (hydrated) THF clusters with low energy electrons (electron energy ~70 eV) in order to study electron ionization and ionic fragmentation. For elucidation of fragmentation pathways, deuterated TDF (C 4 D 8 O) was investigated as well. One major observation is that the cluster environment shows overall a protective behavior on THF. However, also new fragmentation channels open in the cluster. In this context, we were able to solve a discrepancy in the literature about the fragment ion peak at mass 55 u in the electron ionization mass spectrum of THF. We ascribe this ion yield to the fragmentation of ionized THF clusters. Graphical Abstract ᅟ.