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18 April 2022 | Story Leonie Bolleurs | Photo Stephen Collett
Prof Ted Kroon
Prof Ted Kroon from the Department of Physics recently delivered his inaugural lecture on the topic What’s the use of a rainbow on the UFS Bloemfontein Campus.

“A rainbow is a natural phenomenon, the result of the refraction and reflection of the sun’s rays in drops of rain. As far as mankind is concerned, it’s a perfectly useless object and won’t make anyone money. Yet the poet who said, My heart leaps up when I behold a rainbow in the sky, only put into word the feeling of wonder and excitement we all have when we see a rainbow.”

“Every day I see a rainbow in my work; I do not need to wait to see one in the sky,” says Prof Ted Kroon, Professor in the Department of Physics at the University of the Free State (UFS), who used this phenomenon to introduce the topic of his inaugural lecture: What’s the use of a rainbow. 

“Far from being only a colourful spectacle with no practical value, rainbows are useful – and lead to useful things,” he believes. 

According to Prof Kroon, one can find examples of real rainbows and rainbow analogies used not only in everyday life, but also in physics. “Besides it being familiar devices in literature, culture, and even marketing, studies of rainbows can yield practical engineering information and may even help us to find new habitable planets,” he says.

Inspired by the many uses of a rainbow

In his lecture, he discussed the basic features of natural rainbows and how they come about. He also explored how the rainbow gives meaning to colour, and how this relates to the temperature of objects. He looked at an array of instances where the rainbow is used; from depicting the life of a star to indicating that we are sick (a thermometer) or when we need to refill a gas cylinder.
Moreover, Prof Kroon pointed out that rainbows are used in computer chips, stress identification, and to transmit internet data through underwater cables of glass fibre. He also referred to how the rainbow was harnessed as an engineering tool to measure refractive index and characterise fine droplet sprays used in industry. 

He continues, “Remarkably, the science developed to understand the natural rainbow can be redirected and applied to the optical properties of metallic nanoparticles, allowing the development of nanotechnology. Knowing how the natural rainbow works and its limitations, better systems have been developed to produce rainbows. Such rainbows have been used to discover new elements and to determine the age of the universe.”

As a member of an international community of phosphor researchers who are privileged to work with rainbows every day, he has used them to study the light-emitting properties of materials doped with bismuth. With this project – an initiative with the African Laser Centre taking place between 2016 and 2021 – he collaborated with the University of Khartoum in Sudan and trained a number of its postgraduate students. “My role included the guidance of students and the measurement and interpretation of the light-emitting properties of the materials. Our research during this time, considering more than a dozen materials, was summarised in 34 scientific publications that contributed to a greater understanding of bismuth ions as light-emitting materials,” he explains. 

Developing new materials, efficient in emitting blue light

He has been developing luminescent materials since 2006, primarily for general lighting (fluorescent tubes and LEDs) and displays (television, computer, and cellphone screens), as well as niche applications in medical and forensic science. 

As part of his current research, he is examining the effect of plasmonic metal nanoparticles on phosphor light emission. He is also exploring materials that absorb infrared light but emit visible light. “For this, I would like to consider the long-term stability of such materials and develop new materials that are more efficient in emitting particularly blue light,” he says. 

Prof Kroon holds a C2 rating from the National Research Foundation and has published more than 150 articles and book chapters, obtaining a Scopus h-index of 26.

News Archive

Cultivating excellence and success through academics
2011-10-07

 

Unlocking potential. At the Golden Key South African Summit 2011 were, from the left: Dr Derek Swemmer, Registrar (UFS); Prof. Driekie Hay, Vice-Rector: Academic; Mr Ryk Neethling and Ms Charlene Gunter, Director: Golden Key International Honour Society, South Africa.
Photo: Phelekwa Mpono

More than 130 delegates are gathering for the Golden Key, South African Summit at the Bloemfontein Campus of the University of the Free State (UFS). Golden Key International Honour Society recognises academic excellence and uses knowledge to transform lives. It has 400 chapters in eight countries. Of South Africa’s 12 chapters, 11 were present at the summit.

Prof. Driekie Hay, Vice-Rector: Academic at the UFS, welcomed delegates from the respective chapters. She commended them for their perseverance and dedication to excel. “Your academic aspirations and commitment contribute to cultivating a culture of excellence. It will provide a better future for every South African citizen,” she said. Prof. Hay challenged delegates also to “act” by turning their knowledge into actions to advance not only themselves but also society. She also urged them to “discover” everything about themselves, their chosen disciplines, allies and oppositions. “Mostly, you must internalise the spirit of lifelong learning,” she said.

Mr Ryk Neethling, Olympic gold medallist and businessman, was the first keynote speaker. He took everyone through the steps that ultimately led to the moment of victory for him and his team. “We found a way to compete with heart and determination in the 2004 Olympic Games. We were prepared and we took everyone by surprise. “To achieve what one has set one’s mind to, we must dream big,” he said. “Play your part in the team and be confident. Remember that you are victors and not victims,” he urged. He further emphasised the importance of making one’s own luck and, most of all, never to give up.

Another speaker for the summit includes Ms Peggy-Sue Khumalo, former Miss South Africa. Dr Derek Swemmer, Registrar (UFS) will present a workshop on Strategic Action Planning.

This event is the first external lecture that is presented in the Metro’s found in the new Health Sciences Building on the Bloemfontein Campus of the UFS.
 

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