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Nitric oxide assisted C 60 secondary ion mass spectrometry for molecular depth profiling of polyelectrolyte multilayers
Author(s) -
Zappalà G.,
Motta V.,
Tuccitto N.,
Vitale S.,
Torrisi A.,
Licciardello A.
Publication year - 2015
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.7383
Subject(s) - chemistry , sputtering , polyatomic ion , secondary ion mass spectrometry , analytical chemistry (journal) , polyelectrolyte , ion , fullerene , ion beam , mass spectrometry , polymer , nanotechnology , thin film , chromatography , materials science , organic chemistry
Rationale Secondary ion mass spectrometry (SIMS) with polyatomic primary ions provides a successful tool for molecular depth profiling of polymer systems, relevant in many technological applications. Widespread C 60 sources, however, cause in some polymers extensive damage with loss of molecular information along depth. We study a method, based on the use of a radical scavenger, for inhibiting ion‐beam‐induced reactions causing sample damage. Methods Layered polystyrene sulfonate and polyacrylic acid based polyelectrolyte films, behaving differently towards C 60 beam‐induced damage, were selected and prepared as model systems. They were depth profiled by means of time‐of‐flight (TOF)‐SIMS in dual beam mode, using fullerene ions for sputtering. Nitric oxide was introduced into the analysis chamber as a radical scavenger. The effect of sample cooling combined with NO‐dosing on the quality of depth profiles was explored. Results NO‐dosing during C 60 ‐SIMS depth profiling of >1 micrometer‐thick multilayered polyelectrolytes allows detection, along depth, of characteristic fragments from systems otherwise damaged by C 60 bombardment, and increases sputtering yield by more than one order of magnitude. By contrast, NO has little influence on those layers that are well profiled with C 60 alone. Such leveling effect, more pronounced at low temperature, leads to a dramatic improvement of profile quality, with a clear definition of interfaces. Conclusions NO‐dosing provides a tool for extending the applicability, in SIMS depth profiling, of the widely spread fullerene ion sources. In view of the acceptable erosion rates on inorganics, obtainable with C 60 , the method could be of relevance also in connection with the 3D‐imaging of hybrid polymer/inorganic systems. Copyright © 2015 John Wiley & Sons, Ltd.