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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

Outstanding UFS alumni celebrated at annual award ceremony
2016-11-08

Description: Alumni awards 2016 Tags: Alumni awards 2016

Justice Mahube Molemela, Justice Ian van der Merwe
and Tanya Calitz.

The annual Chancellor’s Distinguished Alumni Awards ceremony was presented by the Office of Institutional Advancement on 5 November 2016, at the University of the Free State (UFS) Bloemfontein Campus. The prestigious awards recognise outstanding achievements of UFS alumni provincially, nationally and internationally. These are alumni who have not only placed the university on the world stage but have inspired the next generation of Kovsies and their communities at large.

“I am proud of this year’s award recipients and it is an honour to recognise them for the contributions they make,” said Justice Ian van der Merwe, Chairperson of the UFS Council, at the ceremony. “With these awards, the university wants to strengthen its bond and replenish its connection with alumni, showcase their achievements, and inspire other alumni and students to achieve in their respective fields,” Justice van der Merwe said.

For the first time, the Young Alumnus of the Year Award was presented, to recognise and celebrate the achievements of alumni who have graduated within the past decade. The recipient of the award, Tanya Calitz, Research Lawyer at the Constitutional Court of South Africa, said in her acceptance speech: “At Kovsies you arrive as a student and leave as a critical thinker and leader.”

The Chancellor’s Distinguished Alumnus Award was presented to Justice Mahube Molemela, Chancellor of the Central University of Technology and Judge President of the Free State High Court. “I accept this award with humility and appreciation from this esteemed institution. It is moments like these that we as alumni should reflect on what we can do to contribute to the excellence of the UFS,” said Justice Molemela.

More awards were presented to alumni in the following categories:
•    Rolene Strauss, former Miss World and student at the UFS.
•    Wayde van Niekerk, current world record holder, world champion and Olympic champion in the 400 metres, and student at the UFS.

Cum Laude Award:
•    Neil Powell, Coach of Blitzbokke that won the bronze medal at the Olympic Games in 2016.
•    Professor Eunice Seekoe, Acting Dean: Faculty of Health Sciences, and leader in Health Science professional training.
•    Gary Stroebel, CEO of Central Media Group and visionary media pioneer.

Executive Management Award:
•    Anna Botha (Tannie Ans), coach and mentor of Wayde van Niekerk.
•    Anton Esterhuyse, musical director, composer, arranger, producer, and performer.

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