Faces of CCEB: Justin

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Justin Lim Wei Xiang
PhD Candidate (Chemistry)

To most, a bachelor’s degree in physics would seem daunting. Couple that with a Ph.D. in Chemistry focusing on ultrafast dynamics of two-dimensional semiconductors utilising femtosecond photoemission electron microscopy, would turn even the most ardent science fan away. However, Justin Lim Wei Xiang is not one to shy away from a challenge. 

As a third-year Ph.D. student in Assoc Prof Loh Zhi Heng’s group, Justin won the Best Poster Prize at the International Conference 2026 on Ultrafast Phenomena in Sapporo. He presented his work on how light polarisation could be used to control and alter the behaviour of single anisotropic semiconductor, ReS₂. “In simple terms, we are studying very, very fast processes at very, very short length scales,” Justin adds. “What we are really interested in now is just the fundamental understanding of how the material behaves. They might have some applications five to ten years down the road.”

Having explained his thesis work, Justin shared the experience of attaining first place at the Conference in Sapporo. While he was surprised and elated to get that title, Justin was going with no expectations of winning it. He was hoping to share the science, obtain some pre-review and refine the works afterward. “When you do a poster presentation, you do it to the best of your ability. You don’t really go with the thought of winning. And I was happy because it shows our work was rather well-received.” Justin says.

Amidst the joy in winning, Justin’s path leading to this point reflects on some of the challenges he has had to overcome. As a physics undergraduate who stumbled onto this field of work, he had to learn many chemistry concepts which he had not done so before. Furthermore, for the research and experiment Justin does, every single part of them is an individual field of research, he claims. 

Justin in grateful to have different sources to turn when he seeks clarification. Supervisors, other professors on campus and various academics outside have provided plenty of insight to learn from. An instance when doubt started to creep in was at a previous workshop in Okinawa which focused on photoemission techniques. The analysis of his presentation was not as refined as it was in Sapporo and after meaningful discussions, it got Justin thinking how to interpret the results and better his understanding. “There was a huge debate on how we interpret our data. Have we been understanding our data wrongly? From there, we went back to the drawing board, we came back, talked to our collaborator and our theory collaborators and I also talked to my own supervisor… and make sure we are covering all bases; that we are not just too blindsided on what we are seeing,” Justin explains. 

His journey has also had its fair share of eureka moments. One such moment happened on Christmas Eve in 2024. Apart from his PhD experiment, Justin and his team were developing a high-harmonic generation light source to expand their group’s capabilities in angle-resolved photoemission spectroscopy. As it was a rather fickle technique, many parameters had to be played around with. Many months of tinkering led to nothing. 

However, he persisted and gave a last-ditch effort and tried to detect this light which the team could not see for the longest time. Then came the moment. “We just had a Hail-Mary attempt, and we moved the focus to a particular position, and we suddenly saw that we generated this thing… it was satisfying. And now it is working, so sometimes things happen by random chance,” Justin shares vividly. 

Outside of work, Justin enjoys watching movies and playing games. While he does not have a favourite genre, Justin piques his mind with whatever he finds interesting. Justin also dabbles in photography, going on runs, or having a simple meal with his friends. 

“Many people think that PhD students have no life, and I would say to a certain extent that can be true. But you can do both work and play at the same time. You are not alone in this journey. You can integrate play into work.”

Comparing this version of himself against undergraduate Justin, he has become more critical in thinking whilst also generating ideas on what to study and research on. This pales in comparison when he was focused on just the learning process as an undergraduate. 
“Experimentally, I have grown. Become more skilled, more calculated and precise in the things I do because one gains more experience naturally,” Justin adds.

With just a under a couple of years before he finishes his PhD, Justin hopes to stay in academia and research upon the completion of his graduate thesis. Fuelled by his deep interest in this field, he is now looking forward to pursuing a postdoctoral study to continue his scientific journey.

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Story by Kabir Raj M Kimura Singh, NTU CCEB