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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

Living proof of transformation
2012-07-20

 Prof. Pumla Gobodo-Madikizela (middle) facilitated a dialogue with Archbishop Emeritus Desmond Tutu and Prof. Mark Solms on the Transformation in the Solms-Delta Wine Estate.
Photo: Johan Roux

18 July 2012

“We have the capacity to make a success of South Africa. We have incredible people who refuse to leave the country and want to make a difference.” This is according to Archbishop Emeritus Desmond Tutu who was speaking at the University of the Free State (UFS) today.

Dr Tutu took part in a dialogue with Prof. Mark Solms, owner of the Solms-Delta wine estate in Franschhoek.Prof. Solms is also an A-rated scholar and the Head of the Department of Psychology at the University of Cape Town.The theme of the dialogue was “Living Reconciliation: Winds of Change in Franschhoek and Transformation at Solms-Delta Wine Estate”.

Prof. Solms led an initiative to transform the lives of farm workers on the estate through the Wijn-de Caab Trust. This initiative was extended to empower the wider community of farm dwellers when Prof. Solms co-founded the Delta Trust and the Franschhoek Valley Transformation Charter.

The dialogue was the second in the Dialogue between Science and Society series and was facilitated by Prof. Pumla Gobodo-Madikizela, Senior research professor on Trauma, Forgiveness and Reconciliation at the UFS. The Dialogue series aims to inspire new ways of thinking about responsible citizenship. It also highlights the unique and important ways of engaging with the critical issues of social equality, social justice, social transformation and reconciliation in South Africa.This morning Dr Tutu said the work done in the Franschhoek community is proof that people cannot prosper alone if others are also not prospering. “We belong together. Why did it take us so long to realise it? South Africans have the capacity to make South Africa a better place. It is unacceptable that people go hungry and go to school under trees. It is unacceptable that they still have no books in the third term, and that the pass rate is 30%.

“Is this why we struggled, why people died? We want to go to our graves smiling… we will not be allowed peace and stability if we do not attend to the problems.”

Prof. Solms said the miracle of the political transformation did not trickle down to the people. A lot has been done, but much more needs to be done. “It can only be done by us. It is not the government’s responsibility. The way we live as a result of apartheid is that we are a deeply divided society. We must recognise this and do something to change it.”

He encouraged people to think “small”. An individual cannot change the whole country, but the changes in his community are there to see.

Dr Tutu also congratulated the UFS on becoming a truly South African university, recognising the transformation of the past few years.

The dialogue was presented at the Global Leadership Summit that 250 students and academic leaders from 21 international universities are participating in. The summit runs until Friday 20 July 2012.
 

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