Comparison of fullerene and large argon clusters for the molecular depth profiling of amino acid multilayers

N. Wehbe, T. Mouhib, A. Delcorte, P. Bertrand, R. Moellers, E. Niehuis, L. Houssiau

Research output: Contribution to journalArticlepeer-review


A major challenge regarding the characterization of multilayer films is to perform high-resolution molecular depth profiling of, in particular, organic materials. This experimental work compares the performance of C 60 + and Ar1700 + for the depth profiling of model multilayer organic films. In particular, the conditions under which the original interface widths (depth resolution) were preserved were investigated as a function of the sputtering energy. The multilayer samples consisted of three thin d-layers (̃8 nm) of the amino acid tyrosine embedded between four thicker layers (̃93 nm) of the amino acid phenylalanine, all evaporated on to a silicon substrate under high vacuum.When C60 + was used for sputtering, the interface quality degraded with depth through an increase of the apparent width and a decay of the signal intensity. Due to the continuous sputtering yield decline with increasing the C60 + dose, the second and third d-layers were shifted with respect to the first one; this deterioration wasmore pronounced at 10 keV, when the third d-layer, and a fortiori the silicon substrate, could not be reached even after prolonged sputtering. When large argon clusters, Ar1700 +, were used for sputtering, a stable molecular signal and constant sputtering yield were achieved throughout the erosion process. The depth resolution parameters calculated for all d-layers were very similar irrespective of the impact energy. The experimental interface widths of approximately 10 nm were barely larger than the theoretical thickness of 8 nm for the evaporated d-layers.

Original languageEnglish
Pages (from-to)201-211
Number of pages11
JournalAnalytical and Bioanalytical Chemistry
Issue number1
Publication statusPublished - 1 Jan 2014


  • Argon clusters
  • C
  • Depth resolution
  • Multilayer organic films
  • SIMSdepth profiling
  • Sputtering yield


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