Carbon contamination reduced for ambient-pressure X-ray spectroscopy
Carbon contamination reduced for ambient-pressure X-ray spectroscopy lead image
Advances in X-ray photoelectron spectroscopy have allowed for chemical analyses of surfaces and interfaces at near-atmospheric pressure levels. However, such ambient pressures incur high levels of surface carbon contamination, which can affect end results.
Comini et al. developed a way to reduce or eliminate carbon contamination in these low-pressure experiments by studying titanium dioxide’s interaction with water.
“Hundreds of studies have looked at this interaction before,” said author Zbynek Novotny. “But we’re the first to investigate it in-situ using large single crystals.”
The authors placed a large centimeter-sized single crystal of cleaned titanium dioxide in a vacuum chamber, where they dipped it in ultrapure water that had been outgassed to remove gases such as carbon dioxide. Even under these clean conditions, the authors still found a build-up of carbon equivalent to two graphitic layers when the crystal was dipped into the liquid water.
Testing different methods, the authors discovered they could significantly reduce and mitigate this carbon contamination by introducing oxygen into the vacuum chamber. Additionally, continually rinsing the vacuum chamber walls by repeated exposure to water vapor over several days was found to reduce the water-soluble carbon impurities present and created a cleaner environment with less carbon contamination.
“My team has used the results published in this paper during nearly every experiment done after completing this work,” Novotny said. “We believe our findings are vital for any future experimental work on solid-liquid interfaces using the dip-and-pull technique.”
Source: “Factors influencing surface carbon contamination in ambient-pressure x-ray photoelectron spectroscopy experiments,” by Nicolo’ Comini, Thomas Huthwelker, J. Trey Diulus, Jürg Osterwalder, and Zbynek Novotny, JVST: A (2021). The article can be accessed at https://doi.org/10.1116/6.0001013 .
This paper is part of the Special Topic Collection Commemorating the Career of Charles S. Fadley, learn more here .
