Q: What initially drew you to the APS?

Dugan: I first became interested in X-ray spectroscopy as an undergraduate. It was introduced in a physical methods in inorganic chemistry course, but I didn’t have an opportunity to use it during my PhD, which focused on ultrafast optical spectroscopy.

Over time, I learned that ultrafast techniques could be extended into the X-ray domain at synchrotron facilities. The APS stood out as one of the leading places in the world to do that work, and I wanted to pursue it in my postdoctoral research.

I eventually joined Argonne as a postdoc, working with Lin Chen, one of the pioneers of time-resolved X-ray spectroscopy at the APS. That experience allowed me to explore how X-ray methods could complement the optical techniques I was already using.
 

Q: Can you describe the research you’ve conducted at the APS? 

Dugan: My research at the APS focuses on photochemistry and photocatalysis in systems involving transition metals. We’re interested in how molecules respond to light and how those responses drive chemical reactions relevant to photochemistry and photocatalysis. 

A major part of this work involves X-ray absorption spectroscopy, often in time-resolved experiments. Using synchronized laser and X-ray pulses, we can excite a system and then probe how it evolves, tracking both electronic and structural changes following photoexcitation.

For example, in studies of copper(I) catalyzed photocycloaddition reactions, we’ve used X-ray absorption to follow changes in oxidation state after light absorption. These measurements help identify key steps in the reaction, such as charge transfer processes that initiate chemical transformations. We also rely on steady-state measurements to establish a baseline understanding of the systems we study.
 

Q: What role did the APS play in enabling or advancing your work? 

Dugan: The APS has been essential to this work, particularly because of its time-resolved X-ray spectroscopy capabilities. The APS is the only place in the US where these experiments could be performed, which made the facility uniquely important.

What X-ray spectroscopy adds is a level of specificity that complements optical measurements. Optical techniques provide a broad view of how a system evolves but can be difficult to interpret in detail. X-ray spectroscopy is element-specific and allows us to directly observe changes in oxidation state and local structure around a particular atom.

By combining these approaches, we can build a much clearer picture of what is happening during a photochemical reaction. In many cases, it would be difficult to reach a definitive interpretation using only one technique.
 

Q: Has anything unexpected come out of your work with the APS, either in your results or in the process itself?

Dugan: One of the most interesting aspects of working at the APS is how unpredictable experiments can be. Even with careful planning, things rarely go exactly as expected, and a large part of the process involves adapting in real time.

In terms of results, we’ve encountered cases where the data looked clear but didn’t match our expectations. In one study of an iron-based system, we expected to see a straightforward change in oxidation state following excitation. Instead, the initial measurements suggested a different process entirely.

It was only after extending the measurements to longer timescales that we were able to understand what was happening. The system was evolving through multiple states, and only part of that behavior matched our original assumptions. That kind of result highlights the importance of looking across different timescales and combining complementary techniques.
 

Q: What impact has your research at the APS had on your work so far? What are you excited about exploring next?

Dugan: My work at the APS has shaped the way I approach photochemical systems. It has reinforced the importance of combining different experimental techniques to fully understand complex processes, particularly when studying systems that evolve over a wide range of timescales.

Looking ahead, I’m interested in applying these approaches to more complex and realistic systems, especially those relevant to solar energy applications. As experimental capabilities continue to improve, we can begin to probe reactions under conditions that are closer to how they function in practical applications.

More broadly, I’m excited by how advances at the APS continue to expand what is possible. As beamlines and techniques evolve, they open new opportunities to revisit unanswered questions and explore systems that were previously out of reach.