Understanding gold-thiolate cluster emission from self-assembled monolayers upon kiloelectronvolt ion bombardment

B. Arezki, A. Delcorte, B. J. Garrison, P. Bertrand

Research output: Contribution to journalArticlepeer-review

14 Scopus citations

Abstract

This article focuses on the emission of organometallic clusters upon kiloelectronvolt ion bombardment of self-assembled monolayers. It is particularly relevant for the elucidation of the physical processes underlying secondary ion mass spectrometry (SIMS). The experimental system, an overlayer of octanethiols on gold, was modeled by classical molecular dynamics, using a hydrocarbon potential involving bonding and nonbonding interactions (AIREBO). To validate the model, the calculated mass and energy distributions of sputtered atoms and molecules were compared to experimental data. Our key finding concerns the emission mechanism of large clusters of the form MxAu y up to M6Au5 (where M is the thiolate molecule), which were not observed under sub-kiloelectronvolt projectile bombardment. Statistically, they are predominantly formed in high-yield events, where many atoms, fragments, and (supra)molecular species are desorbed from the surface. From the microscopic viewpoint, these high-yield events mostly stem from the confinement of the projectile and recoil atom energies in a finite microvolume of the sample surface. As a result of the high local energy density, molecular aggregates desorb from an overheated liquidlike region surrounding the impact point of the projectile.

Original languageEnglish (US)
Pages (from-to)6832-6840
Number of pages9
JournalJournal of Physical Chemistry B
Volume110
Issue number13
DOIs
StatePublished - May 6 2006

All Science Journal Classification (ASJC) codes

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

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