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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

UFS Debate Society prepares for three major tournaments
2012-11-20

Preparing for the Berlin Championships are, from the left: Richard Chemaly, Zola Valashiya, Ros Limbo and Nkosi Mangali.
Photo: Linda Fekisi
20 November 2012

The UFS Debate Society will be taking on three major projects during the holidays. The month of December will be filled with activities for the team, with members taking trips to Grahamstown, Pretoria and Berlin, Germany to showcase their debating skills.

Their first project is a coaching session in collaboration with the Free State Schools Debating Board. The team will be coaching the provincial school teams and accompanying them to Grahamstown where they will compete in the National Schools Debating Championships in early December.

At around the same time, members will also attend the Pan African Universities Debating Championships that will be held in Pretoria. The PAN African Championship, which the team won in 2009, has expanded over the years and now also includes participants from Australia and the United States of America.
Towards the end of December, four members of the team will be heading to Berlin, Germany to compete in the World Universities Debating Championships. Ros Limbo, Nkosi Mangali, Richard Chemaly and Zola Valashiya will represent the university.

Zola, who is currently the chairperson of the debating society, has been part of the team since 2008. He describes being part of the teams as, “a growing experience. I have learnt a lot, especially how to be a critical thinker”. He was ranked among the top ten speakers in the English First Language division during the Kgorong 2012 National Universities Debating Championships earlier this year. Zola says the team’s goal is to gain as much experience as possible in order to offer training. They are looking at forming strong relations with various other debate societies across the country.
 

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