Understanding More About ToF-SIMS Analysis & Its Uses

ToF-SIMS (time of flight secondary ion mass spectroscopy) is a powerful surface analytical technique with superior chemical sensitivity, making it helpful in exploring surface chemistry and identifying chemical compositions. With its robust imaging capability, ToF-SIMS can identify the chemicals associated with material failure analysis.

Through the help of sputter ion beam, ToF-SIMS analysis is also used for compositional depth profiling of both organic and inorganic materials. Generally, ToF-SIMS analysis aids in identifying surface chemistry, surface-associated problems, and brings forth a new analytical approach to understanding failure mechanisms in materials.

How does it work?

In ToF-SIMS analysis, a pulsed ion beam is used to sputter the sample’s surface, which then produces secondary particles such as ions, neutral particles, and electrons from the top few atomic monolayers. The secondary ions are collected and accelerated into a flight tube. Their mass is identified by measuring the actual time at the detector – their time of flight.

Since it is possible to measure the time of flight of the particles (from the time of flight to the detector) in nanoseconds, ToF-SIMS can produce high mass resolution mass spectra and identify mass differences as tiny as 0.02 atomic mass units or better. ToF-SIMS is surface sensitive and is a convenient way to make relative comparisons of a given element in different samples. For instance, one can pinpoint that sodium is several times more intense in one sample than in another.

Moreover, the ToF-SIMS analysis technique provides chemical information since it captures all the ions produced in the process of bombardment by the primary ion beam. Thus, it creates unique chemical selectivity for organic materials through the molecular ions allowing one to develop unique analytical approaches to identify chemical structures.

Common applications of ToF-SIMS analysis

Isotopes of elements

ToF-SIMS is used to identify isotopes of elements and molecules. The isotope distribution pattern of a sample is a valuable characteristic for the identification of elements and molecules fragments. For samples that are not isotope enriched, ion mass spectrometry shows the natural abundance of the isotopes.

Ion mass spectrometry of silicone

Silicones are popularly used in the plastic industry and paint systems. In plastics, silicone is used as a release agent, while in paint, it is used as a wetting agent. Therefore, through handling and packaging, silicone is often found as a contaminant on the surface of various objects.

Silicones often cause failure in adhesion and lead to paint defects due to their low surface energy nature. Worse still, even small traces of silicones will migrate to the surface and result in surface contamination. Still, it is easy to determine siloxane contamination thanks to ToF-SIMS analysis and its high surface sensitivity and chemical selectivity.

Paint craters

ToF-SIMS analysis is also valuable for exploring the localization of chemicals on a surface. It is essential in samples where the presence of a chemical is vital but may be ignored due to the weakness of its ions. For instance, paint craters can result from a small perfluorocarbon particle because of its low surface energy. So ToF-SIMS analysis is helpful to study the cause of paint craters. Other agents that result in paint cratering include silicone, detergents, and fatty acids.

Depth profiling

Through the help of a sputter ion beam, the ToF-SIMS technique is helpful in profiling both organic and inorganic substances. A surface is sputtered for a certain period during the process, followed by evaluating the newly produced surface within the sputtered surface. That provides a data point in-depth profile.

Conclusion

ToF-SIMS is commonly used in material science applications to study materials such as pharmaceuticals, polymers, and semiconductors. It is extremely surface sensitive, making it unique in analyzing chemical structures.