Six Decades of Illumination

How did your fascination with chemistry begin?
 

As a child, I was full of questions – asking why things were the way they were. In kindergarten, I remember asking my teacher what holds up the stars, and I was frustrated because she didn’t give me a satisfactory explanation. I knew that light bulbs were in the ceiling, but I didn’t understand how the lights from the stars were held in the sky. 

My father failed chemistry in graduate school and I think that may be one reason why I gravitated towards it, despite his protests. In fact, my parents said that it would only lead to unhappiness, but I was enamored by the chemistry books lying around the house – sneaking them into my bedroom at night and reading under the covers with a flashlight. 

They wouldn’t let me have a chemistry set, so I went to the pharmacy (which these days would be similar to a drugstore) and asked for powdered charcoal, potassium nitrate, and sulfur. The pharmacist asked if I knew what I was doing, to which I said yes – despite setting the basement of my house on fire while meddling with magnesium in the upcoming months and years. But I loved playing around with chemistry and learning how and why reactions occurred.

What was it about light in particular that excited you?
 

When I was studying chemistry and physics at Harvard as an undergrad, I was frustrated because I couldn’t understand light. Seeing is believing and I didn’t understand because I couldn’t see what was happening. As time went on, people would argue about whether light was a particle or a wave – now we know it’s both (sort of), but this wasn’t fundamental knowledge when I was starting out.

I still don’t fully understand how light works, but I have had an increased appreciation and understanding since I was a boy. I think my drive to find an answer has continued throughout my career, and this has pushed me towards optics; in one sense, I wanted to solve the crux of the problem.

You received your PhD in 1964 and are still full time faculty. Have you seen much change as a researcher and professor over the past 60 years?
 

I think students are just as smart and creative today as they’ve always been. However, distractions – television, social media, and so on – have negatively impacted people’s attention span. Everyone’s looking for sound bites of information, as opposed to spending a reasonable amount of time researching a topic. There also isn’t a lot of interest in math anymore. As a whole, I’d say I have seen surprisingly little change. That being said, I’ve been very lucky during my career to work with some wonderful people – both advisors and students.

You’ve collaborated on various projects over the years – can you explore a few of the outcomes?
 

I’m a big advocate for multidisciplinary work – bringing people together with different expertise from different fields is where the biggest breakthroughs occur. In these situations, you’re able to do things together that would be impossible separately – and everybody wins. 

For example, I’ve worked with a medical doctor in China on a health related research project. The regulations for collecting data samples are much more relaxed in China than they are here in the US, so this collaboration granted me access to many different types of medical samples that I wouldn’t have had in solo projects.

I’ve also recently been in collaboration with Basheer Chanbasha, a professor of chemistry at King Fahd University of Petroleum and Minerals in Saudi Arabia, to explore nitrogen fixation. We’re actually able to take nitrogen from the air and turn it into ammonia or urea using water microdroplets striking a catalyst. The outcomes of this are very exciting. There is a long way to go before this might be commercialized, but if we could push this process, we could be looking at something very different to the Haber-Bosch process for producing ammonia. 

Please tell us about laser induced fluorescence – and what you accomplished…
 

When I was a graduate student, I worked with Dudley Herschbach while he was pioneering crossed molecular beams. The experiments looked particularly hard, so I got involved with the theory of molecules – using a mercury lamp to excite vapors of the iodine molecule and make I₂ fluoresce.

The laser was discovered in my lifetime and people didn’t know what to do with it. I decided to use it as a source to excite fluorescence of molecules. Some rather influential people at the time told me to forget it, but I continued to push further because I knew there was potential.  

With more work I discovered that you can capture fluorescence with a photodetector by exciting a sample with a laser. This optical spectroscopic technique is now known as laser induced fluorescence (LIF), and is regularly used to analyze gasses, liquids, and solids..

With LIF, we became the first people to see a single molecule in a solution at room temperature. This was a great achievement that I don’t believe got enough promotion at the time – but it was a breakthrough for the field nonetheless. I knew the future possibilities from LIF were going to be great.

What motivates you – and what keeps you on track?
 

I think what initially drove me was an attempt to please my father and show my worth as a scientist. Though as I’ve worked my way through the field, I think it is a combination of curiosity and the pleasure I receive in sharing new knowledge with others – I believe a lot of others in this line of work will share this sentiment.

Communicating this excitement with others and learning to look at the world differently is an extraordinary thing. In a sense, I think science and art are much more related than people often give credit. As a painter, you’d be frustrated if no one else saw your work, regardless of how much you enjoy creating art. Similarly, when I discover something about nature, I want to share this information with others. For me, it’s about being curious and interacting with others to share exciting knowledge.