X-ray photoelectron spectroscopy (XPS) is the most widely used method for chemically analyzing surfaces. XPS quantitatively provides the elemental compositions, and oxidation states, of the upper 5 to 10 nanometers of surfaces. However, traditional XPS is a high-vacuum technique so sample loading and preparation can be time consuming, and severe limitations are placed on the types of samples that can be analyzed.

Near ambient pressure (NAP)-XPS is a less traditional form of XPS that allows analyses to be performed at relatively high pressures, greater than 25 Torr. As a result, samples can usually be loaded and analyzed in less than five minutes. NAP-XPS significantly expands the types of samples that can be analyzed by XPS to include gases, liquids, foodstuffs, cosmetics, polymers, zeolites, and biological tissues.

In a series of articles in Surface Science Spectra, an international team of researchers from Brigham Young University, Utah, and SPECS GmbH, Germany, has demonstrated NAP-XPS analysis of a series of materials with the first commercial, standalone NAP-XPS instrument. These materials include cheese, a clamshell, a kidney stone, gases, such as oxygen and carbon dioxide, an organic solvent, water vapor, Coca-Cola, bovine serum albumin in water, a mineral, and polymers.

In these analyses, the samples were loaded directly into the instrument without any special preparation, and NAP-XPS yielded the same high quality data that is obtainable with conventional XPS.

“Now you can do XPS on virtually anything,” said author Matthew Linford.

These results contribute to the growing set of spectra in Surface Science Spectra, which is an important database for the surface and materials community.

Source: “Introduction to near ambient pressure x-ray photoelectron spectroscopy characterization of various materials,” by Dhananjay I. Patel, Tuhin Roychowdhury, Varun Jain, Dhruv Shah, Tahereh G. Avval, Shiladitya Chatterjee, Stephan Bahr, Paul M. Dietrich, Michael Meyer, Andreas Thißen, and Matthew R. Linford. Surface Science Spectra (2019). The article can be accessed at https://doi.org/10.1116/1.5109118.