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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

Discussion on decolonising the UFS draws international speakers
2017-11-07


During an insightful two days (27-28 October 2017), bright young minds and experienced thinkers came together at the University of the Free State (UFS) to engage in deep philosophical talks on the topic of decolonisation.  The event was hosted by the university’s Centre for Africa Studies and the Department of Philosophy.

Heavyweight thinkers
Attendees to this colloquium were treated to the thoughts of renowned academics from various social sciences disciplines, including: Prof Francis B. Nyamnjoh, University of Cape Town; Prof Henning Melber, Dag Hammarskjöld Foundation, Nordic Africa Institute, University of London, University of Pretoria and the UFS; Prof Heidi Hudson, UFS; Prof Sabelo J Ndlovu-Gatsheni, University South Africa; Alida Kok, Unisa; and from the UFS Prof Johann Rossouw, Dr Stephanie Cawood, Dr Christian Williams, and Khanya Motshabi. All the speakers had extensive global experience that allowed them to use practical examples to illustrate theoretical ideas. These ranged from students removing colonial spirits with African rituals, incorporating indigenous knowledge systems in curricula, to the creation of cultural houses on campuses where students can become acquainted with different cultures in a safe space.  

 

 Description: Decolonising colloquium bigger Tags: Decolonising colloquium bigger

Questions from attendees at the recent colloquium on decolonising the university,
hosted by the Centre for Africa Studies and the Departement of Philosophy,
showed a search for solutions to the current decolonising dilemma.
Photo: Charl Devenish


Where to from here?
Questions from attendees showed a search for solutions to the current decolonising dilemma. How will it look? Is it possible? Has it worked anywhere? During the two days, it became clear that colonialism reaches far and deep, rendering decolonisation a complex problem that should be addressed carefully to avoid greater divisions. “Colonisers and colonised are two sides of a coin,” Prof Melber explained. “Essentially it means that we are part of the same coin.” This metaphor illustrated how there is no right or wrong world view, or right or wrong knowledge – there should, however, be an integrated approach suitable for that “one coin”. 

It starts at home
Successful decolonisation starts in the mind, it was agreed. Colonisation robbed us all of a richness of knowledge by offering absolutes, or “the only truths”. Questioning existing colonial knowledge and exploring other bodies of knowledge will ultimately lead to a new world of knowledge. Being mediators between the different worlds of knowledge is what the new generation of academics needs to become.  

 

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