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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

Historians must place African history on world stage – Dr Zeleza
2017-05-30

 Description: Historians must place African history on world stage Tags: Historians must place African history on world stage

From the left: Panellists Rev Henry Jackson,
Prof Irikidzayi Manase and Arno Van Niekerk at a book
launch and panel discussion on Africa Day hosted by the
UFS Sasol Library.
Photo: Mamosa Makaya

“African historians must take seriously the challenge of placing African history in world history, and in the history of our species, Homo sapiens.”

With these words, Dr Paul Tiyambe Zeleza, Vice Chancellor of the United States International University-Africa in Nairobi, Kenya, stressed the continent’s challenge.

According to him the contest should continue to recover and reconstruct Africa’s long history. Liberating African knowledges can be done by: “Provincialising Europe that has monopolised universality, universalising Africa beyond its Eurocentric provincialisation, and engaging histories of other continents on their own terms.”

University celebrates Africa Month in various ways  
Dr Zeleza delivered the ninth Africa Day Memorial Lecture, titled The Decolonisation of African Knowledges, at the University of the Free State (UFS). The lecture, hosted by the Centre for Africa Studies (CAS), took place on 24 May 2017 in the Equitas Auditorium on the Bloemfontein Campus and was one of the ways in which the UFS celebrated Africa Month.

Scholars should immerse themselves in these thoughts

Dr Zeleza focused on two issues, which he said were interconnected. They were the unfinished project of decolonising African knowledges and the continent's positioning in global knowledge production.

He said Africa’s scholars and students should “immerse themselves in the rich traditions of African social thought going back millennia”. According to him the continent’s research profile still remains weak in global terms.

“It is imperative that the various key stakeholders in African higher education from governments to the general public to parents, and to students, faculty, staff, and administrators in the academic institutions themselves, raise the value proposition of African higher education for 21st century African societies, economies, and polities.”

“Colonialism is associated with injustice
and inequality, but what happens when
our liberators become our oppressors?”

Library celebrates with panel discussion and book launch
The UFS Sasol Library celebrated Africa Day by presenting a book launch and panel discussion on 25 May 2017, on the pertinent and current political theme of land redistribution with a comparative basis of land invasions in Zimbabwe.

Prof Irikidzayi Manase discussed his book White Narratives: The Depiction of Post-2000 Land Invasions in Zimbabwe, accompanied by Rev Henry Jackson who wrote Another Farm in Africa. A perspective of the economic implications of land redistribution in South Africa was discussed by panellist Arno Van Niekerk: Senior Lecturer of Economics at the UFS Faculty of Economic and Management Sciences.

Inequality still an African problem
The content of the books are a stark reminder of the burning issues of inequality and loss of identity of those who lost their farms in Zimbabwe, a collection of memoirs by white farmers and their families. Rev Jackson gave a religious perspective on reconciliation, forgiveness and the question of land ownership, saying that healing of injustice begins with forgiveness of past transgressions.

Van Niekerk highlighted that while land issues were important, “social cohesion is affected by the economic decisions that will be made”. In closing, Prof Manase called for serious consideration of what the future may hold. “Colonialism is associated with injustice and inequality, but what happens when our liberators become our oppressors?” 

The panel discussion was attended by staff and students of the university, and was lit up by robust discussions on possible historical and future solutions to the question of land, decolonisation and political power struggles in Southern Africa and lessons to be learned from Zimbabwe.

UFS celebrates Africa Month (24 May 2017)

 

 

 

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