A hybrid analyzer integrating the Thermo Scientific Theta Probe XPS and iXR Raman spectrometer is utilized by NEXUS in its materials research. Source: Thermo Scientific

Inside the world-class X-ray photoelectron spectroscopy (XPS) lab at Newcastle University Professor Peter Cumpson and other experts have been providing cutting-edge materials surface analysis to the UK academic community and industry for the past six years.

Cumpson has nearly 30 years of experience working with XPS technology, and he and his team at Newcastle have analyzed a wide and fascinating range of materials, from graphene to meteorite samples, that still show the faint biological footprint of past microbial life, even after 220 million years.

Now, the lab, known as NEXUS—Britain’s National EPSRC (Engineering and Physical Science Research Council) XPS Users’ Service—is eyeing a new frontier in surface analysis. Since June 2016, the NEXUS team has been utilizing an innovative XPS-Raman hybrid instrument that enables simultaneous XPS and Raman spectroscopy from a single point on a sample’s surface. This new evolution in hyphenated techniques is designed to help accelerate innovation in areas ranging from transportation to medicine to solar energy.

The demand for hyphenated techniques

Researchers are trying to solve increasingly complex surface analysis challenges that require more data than a single spectroscopy technique can provide. In situ Raman was the most requested technique in the 2015 NEXUS XPS users’ survey, with 47 percent of the more than 200 respondents asking for this technique. Today, NEXUS users often request analysis of their samples using both XPS and Raman techniques, which provide complementary information about a sample. XPS lets researchers determine the chemistry of a material sample’s surface and how that chemistry changes in the surface and near-surface region. Raman can identify the structure and integrity of 2D materials or the morphology of 3D materials, and provide chemical information about the sample’s composition, defect density and uniformity.  

The challenge has been how to precisely correlate data sets collected using more than one technique, since measuring samples from identical positions without disturbing the material is extremely difficult to perform. That’s why the NEXUS lab team is poised to experience analytical breakthrough by working with the new hybrid XPS-Raman instrument. This instrument seamlessly integrates the Thermo Scientific Theta Probe XPS and iXR Raman spectrometers, allowing the team to perform simultaneous Raman and XPS testing from a single point on a sample’s surface.

Accelerating innovation

Using a hybrid instrument for hyphenated techniques, such as XPS-Raman, allows researchers not only to collect more complete and accurate information and insights into the structure and chemistry of a material’s surface, but also to perform those investigations faster and easier than they could using dedicated instruments for each technique. The ability to get more and better information with increased efficiency could help researchers explore new materials and identify additional uses for established ones.

For example, the NEXUS team’s in-depth investigation of iridium phosphide materials-- which may be a key to more economical and effective solar power--would not have been possible without the unique capabilities of the hybrid XPS-Raman system. Air exposure from transferring the sample between two instruments would have affected the accuracy of the analysis.

The hybrid XPS-Raman instrument could also be particularly valuable for investigating new 2D materials, such as graphene. Graphene, the world’s first 2D material, is also the world’s lightest and most conductive material. Despite its extreme thinness and flexibility, graphene is also 20 times stronger than steel. According to a recent report by Deloitte Global, companies are investing hundreds of millions of dollars into graphene R&D to help them understand this potentially disruptive material and become the first to overcome the challenge of the cost-effective, large-scale manufacturing of graphene in various formats.

NEXUS’s graphene analysis is expanding the scientific community’s insight into the structural and chemical properties of this unique material that has the potential to revolutionize entire industries. Imagine lighter, more fuel-efficient, more protective, rust-free cars, trucks, ships and airplanes, or graphene-coated surgical tools that could kill bacteria and therefore reduce the need for antibiotics, lower postoperative infection rates and speed patient recovery times. Other potential applications, from water purification membranes that could give developing countries clean drinking water, to sensors that could let farmers monitor for gasses harmful to their crops, could have an even greater, positive impact on society.

Hybrid instruments for XPS-Raman and other hyphenated techniques, such as rheology-Raman, will increase in importance over the next decade. Cumpson and NEXUS are taking a leading role in pioneering these developments that will stimulate innovation in all areas of our lives, from the cars we drive to the food we eat.