In our latest interview, AZoMaterials speaks with Carrie Donley, Research Associate and former Director of the Chapel Hill Analytical and Nanofabrication Lab at the University of North Carolina, about XPS for nano/microfabrication and how the Kratos AXIS Supra+ helps to support the lab’s research needs.
Could you please introduce yourself and tell us about your background in spectroscopy?
My name is Carrie Donley, and I’m currently a technical staff member in the Chapel Hill Analytical and Nanofabrication Laboratory (CHANL), a shared instrumentation facility at UNC-Chapel Hill. Within the facility, we see researchers from different disciplines and with different levels of expertise. I help get these researchers the answers they need either by training them to use the equipment or by acquiring data and analyzing it for them.
During my PhD, I was exposed to various types of spectroscopies, but I especially spent a lot of time doing x-ray photoelectron spectroscopy (XPS). Dr. Ken Nebesny was the director of the core facility that housed the XPS at the time, and he gave me great foundational knowledge that I could build upon during my career. Now, as a research associate in CHANL, I use the XPS every day. I especially enjoy interacting with the researchers who use our lab, many of whom are graduate students, and learning about the research they are doing.
Image Credit: Alexander Gatsenko/Shutterstock.com
The Chapel Hill Analytical and Nanofabrication Lab (CHANL) is a core facility dedicated to advancing research for nano/micro fabrication and characterization. Can you tell us more about the lab?
I was the founding director of CHANL, and I started the lab in 2006. We had one scanning electron microscope, a new building where only half of our space was fully renovated, some funding to purchase new equipment, and I was the only staff member. After a lot of work, we now have over 20 major pieces of instrumentation, six staff members, and we occupy 6,600 ft2 of lab space. As a core facility, we are open to users from on and off-campus and have steadily grown our user base over the last 18 years. Our staff all have different areas of expertise, and together we assist users with their research needs.
How is X-ray photoelectron spectrometry (XPS) used for nano/micro fabrication and characterization?
XPS is a surface characterization tool that only samples the top ~10nm of the sample. This makes XPS somewhat unique in terms of sample characterization, and it is especially useful for looking at thin films, changes in surface chemistry, and intentional surface modifications. The majority of our researchers are chemists, but we’ve looked at samples from many other disciplines including physics, geology, pharmacy, biomedical engineering, and environmental sciences, among others.
How does the Kratos AXIS Supra+ instrumentation facilitate the lab’s research needs? Can you tell us more about its specifications?
Our Supra+ system supports our research user base in a number of ways. In addition to traditional XPS work for surface characterization, our system has ultraviolet photoelectron spectroscopy (UPS) capabilities, which allows us to also measure the workfunction and valence band position of materials. I’ve also been exploring the various capabilities of the gas cluster ion source with different materials, both to clean surfaces before analysis and also to do depth profiles. We have the ability to transfer samples into the chamber without exposure to air, allowing us to study air-sensitive samples. Additionally, our analysis stage has heat/cool capabilities, allowing us to study temperature-controlled reactions in situ.
You are hosting an upcoming XPS workshop alongside Kratos Analytical later this year. What are you looking forward to during the workshop and why is it important to hold sessions like these?
I’m looking forward to the workshop because I’m always looking to learn something new. These workshops are important for our users, many of whom are graduate students, because it exposes them to experts in the field, allows them to ask questions, and exposes them to different career options. In addition, it makes potential new users aware of our lab and our capabilities. We’re always looking for new people to work with and new challenges to tackle!
In your own research, you have a number of publications focusing on electrochemical processes and the adsorption of molecules at surfaces. How does XPS analysis facilitate this research?
I’ve been fortunate to work with many different scientific teams over the course of my career. When researchers attach a monolayer to a surface, they need some way to prove that it’s actually there. The surface sensitivity of XPS makes it a perfect tool for this sort of analysis. The subsequent electrochemical processes that occur at that surface can also be very sensitive to surface contaminants. XPS is also great at seeing those potentially unexpected elements on a surface.
What is next for you and the CHANL? Do you have any exciting projects that you are working on currently?
Most recently, I’ve been involved with a project called CHASE – the Center for Hybrid Approaches in Solar Energy to Liquid Fuels, funded by the Department of Energy. This large interdisciplinary research team is headquartered at UNC, but has researchers at six other institutions along the east coast. It consists of 28 principal investigators and over a hundred early career researchers, and our goal is to immobilize catalysts on semiconductor substrates for the formation of liquid fuels from sunlight, CO2, and water. This is exciting work because it could reduce our reliance on fossil fuels and, in the process, reduce the amount of carbon dioxide, a greenhouse gas, in our environment. We use the XPS to confirm that the catalyst molecules are attached to the surface, and to see how those surfaces change following photoelectrochemical processes.
Where can readers find more information?
More information on CHANL and CHASE can be found at the links below:
About Carrie Donley
Carrie was the director of the Chapel Hill Analytical and Nanofabrication Laboratory (CHANL) for 12 years before deciding she wanted to spend more time in the lab. She now oversees many of the
spectroscopy tools in CHANL including the x-ray photoelectron spectrometer (XPS), x-ray diffraction (XRD), infrared and infrared microscope (FTIR), UV-Vis microspectrophotometer (MSP), atomic force microscope (AFM), and the nanoindenter. She holds a Ph.D. in chemistry from the University of Arizona and did postdocs both at the University of Cambridge (UK) and at Hewlett Packard before coming to UNC.
Disclaimer: The views expressed here are those of the interviewee and do not necessarily represent the views of AZoM.com Limited (T/A) AZoNetwork, the owner and operator of this website. This disclaimer forms part of the Terms and Conditions of use of this website.