Aerosol Scientist Spotlight: Dr. Joel Corbin and Dr. Timothy (Tim) Sipkens

By Jenna Ditto, Washington University in St. Louis

In this Aerosol Scientist Spotlight, we highlight a team of government aerosol scientists: Dr. Joel Corbin and Dr. Timothy (Tim) Sipkens from the National Research Council Canada (NRC). Dr. Corbin is a Research Officer on the Aerosol & Gas Metrology team, where he serves as Team Leader. Dr. Corbin earned his PhD from ETH Zurich in Switzerland. Dr. Sipkens is also a Research Officer on the Aerosol & Gas Metrology team. Dr. Sipkens earned his PhD from the University of Waterloo in Canada. Both scientists now live and work in Ottawa, Canada. Here, they tell us about their roles at NRC, their paths towards government research, and their latest science.

To learn more about Joel Corbin: https://nrc.canada.ca/en/corporate/contact-us/nrc-directory-science-professionals/joel-corbin

To learn more about Tim Sipkens: https://nrc.canada.ca/en/corporate/contact-us/nrc-directory-science-professionals/timothy-tim-sipkens

Jenna: Could you give us a little background about the NRC and your Metrology team? What are the big picture questions your team studies?

Joel and Tim: The NRC, in general, works with industry partners and other government departments to advance various research needs for Canadians and the international community. Our team, Aerosol & Gas Metrology, has a background in combustion and aerosol science, which we apply to various topics. Examples include the measurements underlying emissions regulations in the aviation and marine sectors, as well as fundamental aerosol research techniques relevant to wildfires, air pollution (especially black carbon), engineered nanoparticles, and mask efficiency.

In a more practical sense, this means that our work includes the development of entirely new instruments; the improvement of existing instruments; calibration approaches; fundamental research into our understanding of aerosol physics, optical properties, and morphology; and work towards understanding the composition of aerosols from various sources (most recently, aviation engines, marine engines, and wildfires).

We work both in the lab, generating calibration aerosols, and in the field, usually to deploy new calibration methods or techniques. In general, we do metrology in the sense of improving measurements and measurement capabilities.

Jenna: What is the most exciting current research project you are working on together?

Tim and Joel: In recent lab experiments, we’ve produced “black carbon spheres” by charring wildfire-like organics produced by biomass pyrolysis. When partly charred, these could be called “tarballs.” We are excited about these char-black-carbon (char BC) aerosols because we’ve seen evidence for them in many earlier wildfire/biomass-burning studies. Of course, people have charred organics before (whether in an aerosol thermodenuder or in the kitchen). But we have been able to produce black char with zero interference from soot black carbon, allowing us to isolate its properties and instrumental responses. We’ve seen that char black carbon can produce strong signals in all “black carbon” instruments and always has a distinct molecular composition and higher reactivity than soot – even if the soot is brown (immature) and the char is black (more mature). This makes the measurement of BC mass and toxicity for e.g. wildfire smoke non-trivial and also opens the door to new types of calibration particles for BC. In spite of these differences, it was surprising to see that the optical properties of these two classes of light-absorbing-carbon particles (soot and char) can be described by a simple model as progressing from brown to black. The browner the material, the less light it absorbs per unit mass. This opens up several avenues of future research trying to figure out why this might be the case.

Jenna: What are the stand-out elements of your job as a government scientist that are unique to government research? This may be of interest to students considering different career paths after they graduate. 

Tim and Joel: In addition to the obvious fact that our research is often motivated by government priorities, we are also uniquely positioned to work directly with standardization organizations like SAE, ASTM, and ISO. We (particularly Tim) have worked with these organizations to improve the standards by which face masks are tested; the broader team has contributed to an entirely new standard of aviation turbine non-volatile PM emissions over the past decade, and we are currently working with a consortium of European NMIs (national metrology institutes) to standardize light-absorption measurements of BC and other aerosols.

Relative to most university research, it’s also unique that we have technical staff at the NRC with various roles ranging from running experiments, to designing and fabricating parts, to flying research aircraft. This obviously opens doors in a way not possible in smaller academic research groups.

Another couple of examples: it’s much more likely for a scientist to work on one project or topic for multiple years in government than in academia. It’s also possible to switch from classical research (paper writing, etc.) to management (somewhat analogous to the department head at university), or to engage more in standards work (as just mentioned) or client projects.

Jenna: How did you first become involved with government research? Did you always want to pursue government research or did a particular experience during your training inspire you to pursue this career path?

Joel: It was a particular experience. During my PhD, I was working on understanding the ions produced within the soot-particle aerosol mass spectrometer (SP-AMS), which was a fairly new instrument at the time. We ended up taking the SP-AMS to measure aircraft-engine emissions at Zurich Airport, where I met Greg Smallwood, who has since retired from our group. I was happy to talk to Greg about his job as a government metrologist, but never thought I’d be interested myself. It took Greg pointing out that my passion for understanding instrument signals from first principles and figuring out new ways to use those signals is metrology! After that, one thing led to another… I’ve since come to enjoy other facets of metrology, including the design of new systems and engagement with non-experts in various contexts.

Tim: Not immediately. As with many new grad students, I don’t think I fully understood the breadth of opportunities in government. I did have the opportunity to collaborate with the NRC, including on measuring soot using laser-induced incandescence. Through those interactions, I became aware of the role that government researchers can have in the broader community, including their relatively intensive focus on research and their ability to leverage their position to translate research into tangible outcomes.

Jenna: What is your favorite non-research part of your job?

Joel: Not having everyone on the team graduate and change over every 5 years! Though I do enjoy hosting graduate students for research visits. Ottawa is also a great place to live, I can go cross-country skiing in the nearby forest over my lunch hour and there are extensive cycling trails, well separated from any roadways.

Tim: I have to agree with Joel. Having a consistent team of researchers at a range of career stages working closely together to solve big problems is amazing! It is something that is harder to find in academia. This is reinforced by being able to interact with a broad range of experts spanning not just academia, but standardization, policy, and more.