Kiloelectronvolt particle-induced emission and fragmentation of polystyrene molecules adsorbed on silver: insights from molecular dynamics

A. Delcorte, X. Vanden Eynde, P. Bertrand, J. C. Vickerman, Barbara Jane Garrison

Research output: Contribution to journalArticle

65 Scopus citations

Abstract

Polystyrene oligomers adsorbed on Ag{ 111} have been used as a model system for a molecular dynamics study of polyatomic fragment ejection from large organic adsorbates on metals. The simulation of the interaction between the incident 500 eV Ar atoms and the sample predicts the nature and kinetic energy of the characteristic fragments observed in the low-mass range of the experimental polystyrene secondary ion mass spectrum (SIMS). This agreement confirms that characteristic molecular fragments can be the result of a collisional emission process. Moreover, the results indicate that the ejection of intact molecules occurs frequently. To understand the mechanisms of emission of fragments and parent molecules, a representative set of trajectories has been analyzed in detail. The ejection of characteristic fragments is primarily due to the direct interaction between the primary particle and the organic adsorbate. In contrast, desorption of intact molecules is induced by collision cascades in the sample surface. The emission of energetic intact molecules is best explained by a cooperative uplifting mechanism in which substrate atoms with similar momenta push the molecule upward. For comparison to the 500 eV bombardment conditions, simulations conducted with 5 keV primary particles show that large-scale simultaneous motions in the substrate may also occur, inducing the emission of many silver atoms and organic molecules in a single high action event.

Original languageEnglish (US)
Pages (from-to)2673-2691
Number of pages19
JournalJournal of Physical Chemistry B
Volume104
Issue number12
StatePublished - Mar 30 2000

All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry

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    Delcorte, A., Vanden Eynde, X., Bertrand, P., Vickerman, J. C., & Garrison, B. J. (2000). Kiloelectronvolt particle-induced emission and fragmentation of polystyrene molecules adsorbed on silver: insights from molecular dynamics. Journal of Physical Chemistry B, 104(12), 2673-2691.