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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

UFS academic joins an elite league of achievers
2010-04-14

Prof. Dingie van Rensburg, Director of the Centre for Health Systems Research  Development at the University of the Free State
Prof. Dingie van Rensburg
Prof. Dingie van Rensburg, Director of the Centre for Health Systems Research & Development at the University of the Free State (UFS), has joined an elite list of a only few distinguished individuals who have been awarded honorary doctorates by the University of Antwerp (UA) in Belgium.

He is only the third South African to be honoured in this way by the UA, following in the footsteps of Constitutional Court Judge Albie Sachs (2000) and former State President, Nelson Mandela (2004).

He is the first social scientist from South Africa to receive this honorary doctorate from the UA – the highest academic distinction of that university. The university has previously only awarded three honorary doctorates to social scientists: Prof. Raymond Boudon, sociologist at the University of Paris-Sorbonne (1995); Prof. Robert Putman, political scientist at Harvard University (2000); and Prof. John Nash (of A Beautiful Mind fame), mathematician and economist at Massachusetts Institute of Technology (MIT) and Princeton.

The award ceremony will take place on 29 April 2010 in Antwerp.

Prof. Van Rensburg has authored, co-authored and was editor of many books/volumes, chapters in books, monographs, research reports and articles in scientific journals. He has also presented and co-presented at numerous national and international conferences; and supervised a significant number of master’s, doctoral and post-doctoral students.

In his 17 years as director of the Centre he has initiated, managed and led approximately 50 research and development projects, several of them large and long-term projects, and many of an inter-institutional and multidisciplinary nature.

In 2002 he became an NRF-rated researcher and in 2007 his rating as an established researcher was renewed. In the past two decades he received several research grants simultaneously from both the National Research Foundation and the Medical Research Foundation of South Africa, mostly for projects on Tuberculosis, HIV/Aids and antiretroviral treatment.

Prof Van Rensburg holds membership of both the Suid-Afrikaanse Akademie vir Wetenskap en Kuns and the Academy for Science of South Africa; he also served for varying periods on the Councils of both these academies. He was also a member of various health bodies of the Free State Province and the National Science and Technology Forum.

Media Release
Issued by: Mangaliso Radebe
Assistant Director: Media Liaison
Tel: 051 401 2828
Cell: 078 460 3320
E-mail: radebemt@ufs.ac.za  
14 April 2010
 

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