Winner: 2022 Faraday Division Horizon Prize
For the discovery of chiroptical harmonic scattering, theoretically predicted in 1979 and demonstrated experimentally 40 years later.
Celebrate Chiroptical Harmony
A team of scientists from the UK, Belgium and Germany has won the Royal Society of Chemistry’s Faraday Division Horizon Prize for the discovery of chiroptical harmonic scattering, theoretically predicted in 1979 and demonstrated experimentally 40 years later.
When light of a certain colour (frequency f) shines on many materials, they can produce colour-shifted harmonics (frequencies 2f, 3f, 4f, etc.). In 1979, David Andrews, a postdoctoral scientist developed a theory predicting that on illuminating a chiral molecule with circularly polarised light, the intensity of light scattered at such harmonics would depend on the chirality of the scatterers – an effect known as chiroptical hyper Rayleigh scattering (CHRS).
However, for four decades, experimental evidence for such an effect remained elusive.Read more
In 2019, a team at the University of Bath finally reported the first experimental observation of CHRS. Key to this success were the use of highly sensitive equipment and the choice of materials. The team made use of meta-molecules – silver nanohelices much smaller than the wavelength of light, fabricated in the group of Peer Fischer in Germany. Upon illumination with circularly polarized light, it was observed that the intensity of light scattered at the second harmonic (2f) depended on the chirality of the helices.
Chiroptical Harmony’s work provides a straightforward, user-friendly technique for an in-depth characterisation of the light-matter interaction in chiral materials. This type of interaction is crucial for numerous emerging nanotechnologies – including nanorobotics, where the chirality of nanorobots can be used to monitor their functions.
The teamSee full team
David L. Andrews, Professor, University of East Anglia
David R. Carbery, Senior Lecturer, University of Bath
Joel T. Collins, PhD student, University of Bath
Peer Fischer, Professor, Max Planck Institute for Intelligent Systems
David C. Hooper, PhD student, University of Bath
Hyeon-Ho Jeong, PDRA, Max Planck Institute for Intelligent Systems
Robin R. Jones, PhD student, University of Bath
Lukas Ohnoutek, PhD student, University of Bath
Ben J. Olohan, PhD student, University of Bath
G. Dan Pantoș, Senior Lecturer, University of Bath
Fabienne Pradaux-Caggiano, PDRA, University of Bath
Dora M. Răsădean, PhD student, University of Bath
Kristina R. Rusimova, Lecturer, University of Bath
Johannes Sachs, PhD student, Max Planck Institute for Intelligent Systems
Ventsislav K. Valev, Professor, University of Bath
Thierry Verbiest, Professor, KU Leuven University
What was your role within the team?
Kristina Rusimova: "I was involved in the work that led to the original publication, a paper in Physical Review X. At the time, I was a postdoctoral researcher, working closely with PhD student Joel Collins. We prepared the samples and performed the experiments and sample characterisation together."
Robin Jones: "I performed computational simulations of the nanohelices in Lumerical by designing models and establishing simulation conditions. I also participated in analysing the data and preparing the figures and text for the manuscript."
Joel Collins: "I conducted the first round of our HRS-CD experiments and data analysis, as well as researching and designing our initial experimental setup."
Ventsislav Valev: "I led the experimental work on this project – demonstrating the new effects."
David Andrews: "I developed electrodynamic theory for application to the particles that were now under study experimentally, explaining the observations."
What were the biggest challenges in this project?
Kristina Rusimova: "At the start of the project, we were completely in the dark – we had no idea what sample concentrations would be optimal, what filters and sampling rates would be best to use. The biggest challenge for me, as well as possibly my biggest contribution to the project, was to stop changing the experiment half-way, despite the many good reasons to doubt ourselves and stop. Once we decided to keep on track no matter what, we finally obtained a full sweep across the experimental parameters. It was then that we saw a clear trend in our data and the darkness dissipated – all we had to do was to optimise the experimental procedure."
Joel Collins: "Honestly, the biggest challenge was believing those initial results. While the theory predicted this effect decades ago, the symmetry of how we thought our initial experiment was working prohibited the effect. We had to spend a significant amount of time going back over every detail about the experiment, eventually realising that the extremely short pulses of light and a tightly focused beam lead to a symmetry-breaking effect, opening the door to measurable HRS-CD."
What different strengths did different people bring to the team?
Ventsislav Valev: "I see our diversity as a great strength: the team combines physicists and chemists, as well as theorists and experimentalists, of eight nationalities."
Why is this work so important and exciting?
Kristina Rusimova: "Many molecules that are essential to life (e.g. DNA, amino acids) exhibit a handedness called chirality. This chirality can completely change their properties and thus knowing their exact chirality is absolutely vital. This work constitutes the first demonstration of a simple and elegant method of detecting the chirality of both artificial nanostructures and molecules. Not only that, but the effect is 100,000 times more sensitive than its linear counterparts."
Where do you see the biggest impact of this technology/research being?
Ventsislav Valev: "The importance of chirality in biological processes is often compared to the invention of a standardised screw for the industrial revolution. As human-made nanotechnology is progressing, it too requires chirality, for things to fit both together and with the existing biomachinery. It is at this interface, between organic and inorganic chiral technology, that I believe our technology will be most impactful; it could help characterize and guide chirality transfer between organics and inorganics."
How will this work be used in real life applications?
Ventsislav Valev: "There are several potential applications. We are currently working with an industrial partner that manufactures optical instruments, and a major pharmaceutical company is interested as a potential end used of the technology."
What inspires or motivates your team?
Kristina Rusimova: "Ever since I embarked on my career as a physicist I have been fascinated with the search for fundamental understanding of quantum processes on the scale of individual atoms and molecules. The experimental tour de force required for this quest is what got me hooked in the first place and what continues to inspire my research to date."
Robin Jones: "I like being challenged by novel and complex problems to solve. I have always had a passion for learning physics. I ultimately wish to be a valued member of society."
Joel Collins: "Understanding the unusual. At first glance, simple maths prohibits this effect, and yet it was clearly observable. That discrepancy is a huge motivator for me: Something hidden is going on, and we get to find out what it is!"
What is the importance of collaboration in the chemical sciences?
Fabienne Pradaux-Caggiano: "Collaboration in chemical sciences allows people from different disciplines but with common interests to come together and join forces to make research move forward."
Dora Răsădean: "Chemical sciences cannot be separated from other life sciences as collaboration is essential to having a comprehensive strategy when tackling both research and industrial aspects of chemical sciences."
Dan Pantoș: "Modern science cannot exist without collaboration. While this is a truism, we frequently find ourselves speaking "different" languages whether we’re chemists, physicists, biologists, etc. Collaboration allows us to understand each other and benefit from our collaborators’ experiences and knowledge. It also allows us to see the scientific problem from different points of view which leads ultimately to a better understanding and to a comprehensive solution/answer to the original scientific question we’ve asked."
How are the chemical sciences making the world a better place?
Thierry Verbiest: "Chemistry has a bigger impact on our daily lives than most people think. Just think of the development of new plastics, medicines, health care products, microchips, fuels, etc... But perhaps the biggest challenge crucial for our society is sustainability and the environment."
What advice would you give to a young person considering a career in chemistry?
Fabienne Pradaux-Caggiano: "I would say that they should embrace it with both arms and see where it leads them. There are so many different specialties and subjects that you can’t be sure at the start what you will enjoy the most. The opportunities are endless."
Dora Răsădean: "The advice I always give to students wanting to pursue a career in chemistry is to be passionate, integrous and responsible about what they are doing, knowing that their today’s work can help somebody tomorrow or decades latter. I tell them never to be afraid of failure as some of the most amazing chemical discoveries are the results of many trials and errors."
Dan Pantoș: "Be curious, don’t be afraid to ask "why" and keep an open mind. Study all areas of chemistry because there is not a single one that is not useful or impactful."