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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 gives recognition to excellent researchers
2004-11-16

p>The University of the Free State will give recognition to excellent researchers at UFS on Tuesday 16 November 2004. “This recognition function will also serve as the first annual lecture in research excellence,” says Prof Frans Swanepoel, Director of Research Development Division at the UFS.

 

This is the first occasion of its kind in the UFS. It coincides with the university’s centenary celebrations. The recognition of excellent research shows the UFS’s commitment and innovative focus on research as one of its core functions,” says Prof. Swanepoel.

Recognition will be given in different categories. They are female researchers, black researchers, young researchers, C- and L-Rated researchers, researchers with significant research outputs, B-Rated researchers and distinguished professors in research.

The promotion of equity and development of research capacity of designated groups is one of the objectives of the UFS’s research strategy therefore the university is recognising the research achievements of 21 women and 16 black persons. Amongst these are Prof. Margaret Raftery (English and Classical Languages), Dr Liesl van As (Zoology and Entomology), Prof. Peter Mbati (head of the Qwaqwa campus) and Prof. Charles Ngwena (Constitutional Law and Philosophy of Law).

The UFS is also recognising nine young researchers. They must hold a doctorate and have the potential to establish themselves as researchers within a five-year period based on their performance and productivity as researchers during their doctoral studies and/or early post-doctoral careers. Amongst them are Dr Esta van Heerden (Microbial Biochemical and Food Biotechnology) and Prof. André Jooste (Agricultural Economics).

Fifty-eight established researchers with a sustained recent record of productivity are receiving recognition in the C- and L-rated researchers’ category. Amongst them were Prof. Hennie van Coller (Afrikaans, Dutch, German and French) and Prof. Gert Erasmus (Animal- and Wildlife- and Grassland Sciences).

Prof. Francois Tolmie (New Testament) and Prof. Gina Joubert (Biostatistics) are two of the twelve researchers that are receiving recognition for having excelled in research outputs during recent years.

Nine researchers are acknowledged in the B-category for the international recognition they receive from their peers for the high quality and impact of their recent research outputs. Amongst them were Prof. Johan Grobbelaar (Plant Sciences) and Prof. Hendrik Swart (Physics). Prof. Grobbelaar focused in his research on limnology, algal biotechnology, plant stress and Prof. Swart focused on solid state physics and degradation mechanisms that are responsible for the degradation of field emission and TV displays.

Seven individuals are recognised for their exceptional achievements as researchers. Prof. Frederick Fourie, Rector, but previously in the Department of Economics, is recognised for his research in two policy areas: Political Economics, Government Finance and Fiscal Policy, and Industrial Economics, in particular analysis of the South African industrial structure and competition policy, where his research contributions played a key role in reforming South Africa’s competition policy.

Prof. Lodewyk Kock (Microbial, Biochemical and Food Biotechnology) focuses in his research mainly on pure and oxidised edible oil where yeasts are used as a study model. He obtained national as well as international recognition for this research program.

The UFS is also awarding the S2A3 Bronze Medal to recognise a Master’s degree student who has delivered outstanding research in one of the sciences. Mr Pieter Taljaard and Ms Tania Venter are recognised in this category.

Media release
Issued by: Lacea Loader
Media Representative
Tel: (051) 401-2584
Cell: 083 645 2454
E-mail: loaderl.stg@mail.uovs.ac.za
16 November 2004

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