EAIFR’s Ndengué brings experience in quantum dynamics to photocatalytic water splitting project

by Carey Sargent, EPFL, NCCR MARVEL

Steve Ndengué, now Senior Lecturer in the Condensed Matter Physics section of the East African Institute for Fundamental Research, grew up and went to high school in Douala, Cameroon. He moved to the University of Buea for his undergraduate studies before returning to Douala once again to complete his master’s degree and then completing a PhD in Condensed Matter and Radiation at the University of Grenoble in France on the topic of isotopic selectivity in ozone photodissociation. Following his PhD, he first held a Lecturer and Senior Lecturer positions at the University of Douala and then spent several years in the U.S. as a postdoctoral researcher in the Chemistry Dept. group of Richard Dawes at Missouri S&T, near St. Louis. He was then offered a faculty position at ICTP-EAIFR, where he has been ever since. When he had free time, he played basketball. Though he has very little spare time these days, he does try to scour social media to try to understand where the technology community is going, particularly in terms of quantum computing and machine learning.

Have you always been interested in science?

I can’t say that I always had a very strong interest, but I was always really good at mathematics—I used to enjoy playing with numbers and these kinds of things. When I arrived in the last few years of high school, we started studying physics and for some reason it was a bit of a challenging topic and so I decided to try to study it a little bit more. And that’s why I decided to go to physics at the university rather than doing mathematics. It wasn’t specific curiosity about science though, it was just an interest in math and then realizing that in physics there is this possibility of using math to do something that looks a little more concrete. And as time went by, I started enjoying it even more.

What appeals to you about being a scientist?

As I said, I was strongly interested in math and as I was finishing high school, I was interested in going into banking for some reason. But when I started university, it seemed to be easier, back in Cameroon, to go into physics at the time for me than to do banking. I didn’t see a lot of pathways between the two when I was studying, with very few opportunities and options. But once you start and are actually good at it, you start seeing that there are more and more opportunities, to the point where you end up with a PhD and getting a faculty position. But it felt like the most logical pathway, there weren’t so many options or choices.

What is the main focus of your current research?

Currently what I’m looking at is quantum dynamics. Specifically, what is very interesting and I spend a lot of time thinking about is the fact that it’s a very useful process—the most accurate way of describing the physics of several microsystems—but unfortunately the computational resources required for these kinds of studies are not available. This is why we have to spend a lot of time thinking about better ways of describing those problems. I’m essentially working on describing scattering problems with involved techniques using new ideas that involve contraction of matrices and very efficient quantum dynamics with limited resources. There are many types of applications, in catalysis, in photochemistry, but the core idea is how can we make some expensive calculations more affordable, using the resources that we have available. 

Which publications are you most proud of?

1. Electric response of endohedrally confined hydrogen atoms

The first one is the very first publication that I had. It was a few months before starting my PhD and so I was still a master’s student. I had started working on a project with my supervisor back in Cameroon and we managed to get a paper published in Journal of Physics B and it was very exciting because I was not even a PhD student yet. We worked on that project, the paper was submitted and in less than a month it was accepted with almost no revisions. It was a strong motivation factor to continue doing research. I’m particularly proud of that one because I didn’t know anything about that environment or that world yet.

2. Ozone photolysis: Strong isotopologue/isotopomer selectivity in the stratosphere

Then, after that, I would say it is the last publication of my PhD, which was actually an interdisciplinary publication. We published it in the Journal of Geophysical Research, which was more or less a summary of what I did during my entire PhD.  That one I liked specifically because I was able to connect what I did to one or two different area and it was a good summary of what we had done for the last three years. It took some time to convince them to publish it, but it has been quite well cited and was appreciated by the referees in the end.

3. Atom-triatom rigid rotor inelastic scattering with the MultiConfiguration Time Dependent Hartree approach

The third one is a small paper that we published. I applied a method to study a new kind of problem that’s related to inelastic scattering and it’s important because it was more or less establishing a signature of the kind of research that I can do. It was something very singular, upon my own direction and motivation. It was very original research and different from what has been done before. I’m proud of it because it’s also opening pathways for many other research paths we are looking at right now in my group.

Anything else to add?

I just wanted to express an appreciation for this grant that brings EPFL scientists together with scientists in Africa and having the possibility to connect and try to learn from each other. It’s a bit unique and really appreciated and I’m looking forward to what is coming next in terms of future opportunities that can come from this type of collaboration and interaction.

References:

SA Ndengué, O Motapon, Electric response of endohedrally confined hydrogen atoms Journal of Physics B: Atomic, Molecular and Optical Physics 41, 045001

S Ndengué, S Madronich, F Gatti, HD Meyer, O Motapon, R Jost, Ozone photolysis: Strong isotopologue/isotopomer selectivity in the stratosphere, Journal of Geophysical Research: Atmospheres 119 (7), 4286-4302

Ndengué, Steve, et al., Atom-triatom rigid rotor inelastic scattering with the MultiConfiguration Time Dependent Hartree approach, Chemical Physics Letters 668 (2017): 42-46.