A valuable qualitative tool finds new applications

Time of flight secondary ion mass spectrometry (TOF-SIMS) is a sophisticated surface-sensitive technique used extensively for qualitative analyses. One of its most attractive features is the time required for analysis. Results from TOF-SIMS testing are often obtained in minutes while other analytical methods, including X-ray photoelectron spectroscopy and auger spectroscopy, commonly require hours to yield results.

Although TOF-SIMS is viewed as a valuable qualitative tool, it has earned a faulty and undeserved reputation as non-quantitative. Spool and Finney addressed this misconception and presented evidence of the repeatability, replicability, and reproducibility of the quantitative aspects of TOF-SIMS.

“We explored methodically how variations in such things as sample mounting and orientation will affect the quantitative results,” said author Alan Spool.

Using an IONTOF M6 instrument to analyze the surface of a magnetic recording disk, the researchers tested which factors produced the largest errors while reproducing TOF-SIMS experiments, including how tilting samples can affect readings related to macroscopic topography.

Repeatability — the main challenge in performing a quantitative analysis — can be achieved by creating a standard protocol. The protocol should include the acquisition setup, analyzer and primary ion gun settings, primary ion current, and dose. Macroscopic topography should be controlled as much as possible.

Replicability can be established by sharing analysis protocols, training, and samples of varying concentrations between two or more laboratories. Reproducibility between different models of TOF-SIMS instruments can be established after adjusting analysis protocols.

“We hope that researchers and practitioners in industrial laboratories will find this paper helpful in using TOF-SIMS quantitatively,” said Spool.

Source: “Best practices for performing quantitative TOF-SIMS analyses” by Alan M. Spool and Lorie Finney, JVST: A (2024). This article can be accessed at https://doi.org/10.1116/6.0003660 .

This paper is part of the Reproducibility Challenges and Solutions II with a Focus on Surface and Interface Analysis Collection, learn more here .