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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

Golden Key Chapter of the UFS walks away with gold status
2011-10-13

 

This generation has to find a mission, something they can be as passionate about as their predecessors of the 1970s were. A greater nation has just risen. At the 2011 South African Golden Key Summit, were from left: Mr Ruddy Banyini, outgoing President: UFS Chapter; Mr Puso Thahane, President: Wits Chapter, and Mr Katleho Mohono, Vice-President (Internal): Wits Chapter.
Photo: Leonie Bolleurs

Our university earned gold status as one of the top chapters in the country. This was one of four awards won by the UFS at the 2011 South African Golden Key Summit held at the Bloemfontein Campus from 6-8 October 2011.

Mr Ruddy Banyini, outgoing  Golden Key president (UFS) and the president of the Wits Chapter jointly received the Regional Student Leader of the Year award. The UFS Chapter also took third place for Best Community Service as well as for Best Campus Awareness Initiative. This follows hot on the heels of the chapter winning the Golden Key International Chapter Service Award for the second consecutive year in May 2011.
 
The summit also yielded some new challenges for all chapters. Mr Banyini and his counterparts from the University of Witwatersrand are on a mission to cultivate a nation of thinkers. This follows the successful hosting of a Thinkers Symposium by the Wits Chapter to determine the contribution thinkers could make towards shaping a better society. “This initiative will see all students on campus mobilised and actively participating,” Mr Banyini said. “Thoughts without action are just thoughts. We are all aware of social ills in our country, yet only a few come forth with a solution,” stated Mr Katleho Mohono (Wits).
 
The involvement of Golden Key members in helping to create solutions for national problems has triggered a series of think-tank symposiums organised by various chapters. The result has been an exponential growth in the numbers of those collectively involved in the on-line National Planning Commission’s consultative forum. “The impact of mobilising the best current academic achievers in Higher Education opens up exciting new possibilities through constructive student engagement with society’s issues,” Dr Derek Swemmer, Registrar at the UFS,” said.

 

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