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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

NRF researcher addresses racial debates in classrooms
2017-03-24

Description: Dr Marthinus Conradie Tags: Dr Marthinus Conradie

Dr Marthinus Conradie, senior lecturer in the
Department of English, is one of 31 newly-rated National
Research Foundation researchers at the University of
the Free State.
Photo: Rulanzen Martin

Exploring numerous norms and assumptions that impede the investigation of racism and racial inequalities in university classrooms, was central to the scope of the research conducted by Dr Marthinus Conradie, a newly Y-rated National Research Foundation (NRF) researcher.

Support from various colleagues
He is one of 31 newly-rated researchers at the University of the Free State (UFS) and joins the 150 plus researchers at the university who have been rated by the NRF. Dr Conradie specialises in sociolinguistics and cultural studies in the UFS Department of English. “Most of the publications that earned the NRF rating are aimed to contributing a critical race theoretic angle to longstanding debates about how questions surrounding race and racism are raised in classroom contexts,” he said.

Dr Conradie says he is grateful for the support from his colleagues in the Department of English, as well as other members of the Faculty of the Humanities. “Although the NRF rating is assigned to a single person, it is undoubtedly the result of support from a wide range of colleagues, including co-authors Dr Susan Brokensha, Prof Angelique van Niekerk, and Dr Mariza Brooks, as well as our Head of Department, Prof Helene Strauss,” he said.

Should debate be free of emotion?
His ongoing research has not been assigned a title yet, as he and his co-author does not assign titles prior to drafting the final manuscript. “Most, but not all, of the publications included in my application to the NRF draw from discourse analysis of a Foucauldian branch, including discursive psychology,” Dr Conradie says. His research aims to suggest directions and methods for exploring issues about race, racism, and racial equality relating to classroom debates. One thread of this body of work deals with the assumption that classroom debates must exclude emotions. Squandering opportunities to investigate the nature and sources of the emotions provoked by critical literature, might obstruct the discussion of personal histories and experiences of discrimination. “Equally, the demand that educators should control conversations to avoid discomfort might prevent in-depth treatment of broader, structural inequalities that go beyond individual prejudice,” Dr Conradie said. A second stream of research speaks to media representations and cultural capital in advertising discourse. A key example examines the way art from European and American origins are used to imbue commercial brands with connotations of excellence and exclusivity, while references to Africa serve to invoke colonial images of unspoiled landscapes.

A hope to inspire further research
Dr Conradie is hopeful that fellow academics will refine and/or alter the methods he employed, and that they will expand, reinterpret, and challenge his findings with increasing relevance to contemporary concerns, such as the drive towards decolonisation. “When I initially launched the research project (with significant aid from highly accomplished co-authors), the catalogue of existing scholarly works lacked investigations along the particular avenues I aimed to address.”

Dr Conradie said that his future research projects will be shaped by the scholarly and wider social influences he looks to as signposts and from which he hopes to gain guidelines about specific issues in the South African society to which he can make a fruitful contribution.

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