Primary-ion-induced fragmentation in organic molecules can strongly influence the results in secondary-ion mass spectrometry (SIMS) of organic and biomolecular samples. In order to characterize this ion-induced fragmentation, oligopeptide samples irradiated in SIMS experiments were investigated by means of desorption/ ionization induced by neutral SO 2 clusters (DINeC). The latter is a nondestructive desorption method for mass spectrometry of biomolecules, which gives direct access to the fragments induced in the sample. Comparison of TOF-SIMS and DINeC mass spectra revealed qualitative differences between the fragments, which remain in the sample and the fragments sputtered during ion bombardment. The fragmentation strength and its spatial distribution were found to be quantitatively different for Bi 1 + , Bi 3 + , and Ar 1000 + primary ions, leading to different distributions of the degree of fragmentation in the samples as directly measured by means of DINeC depth profiles.
Soft
cluster-induced desorption/ionization of polystyrene oligomers
was investigated with respect to application in mass spectrometry.
Clear peak progressions corresponding to intact polystyrene molecules
were observed in the mass spectra, and no fragmentation was detected;
efficient desorption was deduced from quartz crystal microbalance
measurements. Molecular dynamics (MD) simulations of the process revealed
that even in the case of the nonpolar polystyrene molecules cluster-induced
desorption proceeds via dissolvation in the polar clusters. Experimentally,
a significantly lower desorption efficiency was observed for polystyrene
molecules with larger chain length. Taking into account MD simulations
and further experiments with mixed samples consisting of long- and
short-chain polystyrene oligomers, the reduced desorption efficiency
for longer chain polystyrene molecules was attributed to a stronger
entanglement of the larger polystyrene molecules.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.