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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

Internationally acclaimed academic applauded on Africa Day
2011-06-02

 
 Prof. Ali Mazrui, an internationally acclaimed and renowned academic.

One of the world’s top academics was given a warm welcome in the rather cold Free State recently.

Prof. Ali Mazrui, an internationally acclaimed and renowned academic, visited us as part of our Africa Day celebrations as arranged by the Centre for Africa Studies. He delivered a keynote address, entitled ‘Pro-democracy uprisings in an African experience: from Sharpeville to Benghazi.’

A festive atmosphere and the sound of drums welcomed this intellectual giant as well as other delegates upon their arrival at the CR Swart Auditorium on our Bloemfontein Campus. Some of the delegates who attended the Africa Day Celebrations, included: Mr Tom Amolo, High Commissioner from the Republic of Kenya; Mr Dan Kgothule, MEC of Arts and Culture in the province; Prof. Jeff and Dr Carla Ramsdell, visitors from America; Dr Allan Boesak and Prof. Nicky Morgan, Vice-Rector: Operations.

Prof. Frederick Fourie, former Vice-Chancellor and Rector of our university, also attended the celebrations, as did some scholars from neighboring schools.

Welcoming Prof. Mazrui, Prof. Jonathan Jansen, Vice-Chancellor and Rector of our university, quipped that he was relieved the world had not ended the previous weekend as was predicted, because he was looking forward to listening to such a renowned intellectual.

Prof. Lucius Botes, Dean of Humanities, followed Prof. Jansen at the podium. He said the ability to go from following a bridging course to being one of the top 100 intellectuals in the world, indeed distinguishes Prof. Mazrui as an exceptional academic. This intellectual is, among others, an Albert Luthuli Professor at the University of Jos, Nigeria and Andrew D. Professor Emeritus and Senior Scholar in Africana Studies at Cornell University.

In his introduction, Prof. Mazrui said he feels honored and flattered by this opportunity. He proceeded by referring to the history of Africa Day and added that he would rather prefer an Africa Week to an Africa Day to ensure that everybody has the opportunity to celebrate the continent.

He sang the praises of South Africa, as almost every other African country which attained liberation from European colonial rule in the 20th century, has been unable to maintain its democratic order beyond its first decade of independence.

“The Republic of South Africa, on the other hand, liberated Nelson Mandela in 1990, held its first democratic election in 1994, and already has its third president. Nearly two decades after Apartheid, South Africa has not outlawed opposition parties, or experienced a military coup, or permitted the Head of State to govern the country as a dictator.”

In his speech he compared the uprisings in Sharpeville during 1960 and Soweto during 1976 with the more recent pro-democracy uprisings in North Africa, based on the role that weapons and the lack thereof, as well as the youth and women played in the respective cases.

He concluded by saying the uprisings in Tunisia and Egypt have already resulted in ousting dictators who had been entrenched in power for decades, adding that in Libya a third dictator’s future is on the line. “Never in the history of the Arabs have there been so many popular uprisings which seem to be inspired neither by Islam nor by anti-imperialism, but in the quest for liberal reforms. Half a century earlier in Sharpeville and Soweto, South Africans experienced their own political awakening.”

Prof. Kwandiwe Kondlo, Director of the Centre for Africa Studies, closed the event with a word of thanks to the American academic and his wife, guests and attendees. He said discussions prior to the event revealed that more research has to be done regarding gender issues on the continent.

Prof. Mazrui also participated in conversations at the institute and a media briefing which was hosted earlier the day.

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