TOF-SIMS (time-of-flight secondary ion mass spectrometry) is surface sensitive and often has chemical sensitivity, making it a powerful surface analytical method. Because of that, it is unique when it comes to exploring surface chemistry and identifying chemical structures.
With the imaging ability, TOF-SIMS analysis helps analyze materials failures where the identification of materials and pinpointing their localities is needed. Helped with a sputter ion beam, time-of-flight secondary ion mass spectrometry can profile organic and organic materials, allowing the exploration of chemical variability without prior knowledge of samples under investigation.
Principles
TOF-SIMS, also called static SIMS, is related to dynamic SIMS that uses a constant beam of ions to etch a sputter crater in a sample for a period of time. On the other hand, TOF-SIMS often uses pulsed and focused ion beams and doesn’t damage the sample’s surface. This makes the TOF-SIMS technique suitable for the analysis of surfaces.
When combined with other techniques, TOF-SIMS provides great survey abilities with sensitivity in the ppm (part per million) range. The pulsed ion beam used in the time-of-flight secondary ion mass spectrometry instruments is focused to sub- µm dimensions. That means you can use the technique to analyze features in a range between 1µm and 500µm. Both insulating and conducting samples can be successfully analyzed.
Sample Preparations and Requirements
TOF-SIMS is used on many solid-state types of samples. A larger solid can easily be analyzed, and powered ones can press Indium plates before they are analyzed.
In general, every TOF-SIMS sample must be handled cautiously in order to prevent contamination. For instance, plastic tools and containers must be avoided during handling.
- Strengths of TOF-SIMS
- Non-destructive analysis
- Surface analysis of conducting and insulating samples
- High sensitivity for trace compounds or elements
- Retrospective analysis is required for the interpretation of stored spectra and images
- High mass resolutions for distinguishing species of the same nominal mass
- Surveys of masses on the material surfaces
Applications
The world today is often characterized by continuous technological change and development. Understanding capacity and taking advantage of some new ideas is important. Because of that, analytical instrumentation must expand its performance in order to fulfill future and current analytical demands.
As of now, TOF-SIMS supports many different industries. Apart from aerospace, solar, automotive, and electronics, other industries may include the following:
- Atmospheric sciences – Through TOF-SIMS, aerosol particles are 3D images with a higher spatial resolution to elucidate their mixing state.
- Environmental microbiology – TOF-SIMS offers 3D tracing of small functional organic materials and interesting elements affecting pollutants cleanup or generating biofuels in microorganisms, like microbial colonies.
- Biogeochemistry – TOF-SIMS is used for 2D (two-dimensional) molecular mapping of rhizosphere so as to elucidate root-mineral-organic matter-microbe interactions. Combining TOF-SIMS and analysis of principle components may reveal active adsorption sites of different organic materials on the mineral surfaces.
The Bottom Line
TOF-SIMS remains a functional and versatile analysis technique, which may provide depth profiling, 3D & 2D images, and chemical composition. Apart from qualitative measurements of the lignocellulosic biomass, TOF-SIMS may as well supply relative quantification of chemical compositions by comparing the ratio of different peak intensities.
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