Depth profiling of Langmuir-Blodgett films with a buckminsterfullerene probe

Audra G. Sostarecz, Carolyn M. McQuaw, Andreas Wucher, Nicholas Winograd

Research output: Contribution to journalArticle

53 Scopus citations

Abstract

Bombardment with C60+ primary ions of monolayer and multilayer barium arachidate Langmuir-Blodgett (LB) films is investigated. The behavior of cluster versus atomic (Ga+) bombardment is monitored by the barium-cationized arachidate ion (mass-to-charge ratio (m/z) 449) and a characteristic fragment ion (m/z 209) using 1-, 7-, and 15-layer model systems. The removal rate of material from the films is shown to be on the order of several hundred molecules per C60 impact, a value 100-fold larger than Ga+ impact. The enhancement in secondary ion yield is also shown to be larger for the 15-layer film (400x) than for the monolayer film (100x). Moreover, most of the increase in yield is shown to be associated with ejection of sputtered species rather than an increase in ionization probability. High yields associated with cluster bombardment are also shown to be amenable to depth profiling experiments in which the two ions can be monitored as the film is being removed. In this modality, chemical damage associated with bombardment is removed before it can accumulate on the surface. Due to the similarity of fatty acid LB films to cellular membranes, these results suggest that C 60+ primary ion beams may improve the prospects for TOF-SIMS studies of biological systems.

Original languageEnglish (US)
Pages (from-to)6651-6658
Number of pages8
JournalAnalytical chemistry
Volume76
Issue number22
DOIs
StatePublished - Nov 15 2004

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All Science Journal Classification (ASJC) codes

  • Analytical Chemistry

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