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Animation showing how time of flight secondary ion spectrometry works. Credit: ION-TOF, GmbH
Surfaces are of critical importance in materials systems and devices. One very powerful tool for the analysis of surface and subsurface chemistry is time of flight secondary ion mass spectrometry, which offers ppm or better sensitivity, less than 1 nanometer surface specificity, the ability to collect rapidly a full mass spectrum at every volume element and the ability to collect 2D images at every depth in a depth profile measurement.
The January/February 2012 issue of the Bulletin has an article on TOF-SIMS that shows how the technique can provide key surface information about materials and the wealth of information TOF-SIMS data sets provide.
The author, Vincent Smentkowski, is a surface chemist/analyst at the General Electric Research Center in Niskayuna, N.Y, and for the past nine years, his work has focused on TOF-SIMS characterization of materials.
Over the last decade, improvements in the instrumentation allow for detection of all elements, including hydrogen, sensitivity in the ppb range under certain conditions and the ability to probe surfaces at nanoscale depths.
In an email, Smentkowski said, “I routinely find unexpected species/contaminants in the samples I analyze by TOF-SIMS. An important aspect of my work involves the use of multivariate statistical analysis tools in order to perform a rapid, unbiased, and complete analysis of the full TOF-SIMS data sets. MVSA algorithms allow for the identification of species association in complex multiphase materials.”
In his article, Smentkowski uses examples from GE studies to show how TOF-SIMS was used to discover unexpected contaminants in an alumina insulator, profile the cross-section of a SOFC (including the lightweight elements sodium and hydrogen), map elemental distribution and segregation on functionalized iron oxide particles and more.
The animation above (provided by instrument manufacturer, ION-TOF, GmbH) shows how ions are pulsed from the ion gun and bombard the sample, causing ions to be released from the specimen surface and subsequently detected and analyzed.
Be sure to read the article to learn more about TOF-SIMS and its capabilities. It may prove to be a valuable tool for your consideration, too.
Print copies will be in the mail by January 1, and the e-magazine will be available online in early January.