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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

Researchers urged to re-emphasise regeneration of grassroots
2013-10-23

23 October 2013

Institutions of higher learning have a critical role to play in the promotion and protection of indigenous knowledge systems. This is according to Dr Mogomme Masoga, UFS alumnus and Senior Researcher with the Development Bank of Southern Africa (DBSA).

Dr Masoga was addressing the 6th annual Indigenous Knowledge Systems (IKS) Symposium at the University of the Free State’s Qwaqwa Campus.

“The time has come for local communities rich with knowledge to be taken seriously by the researchers doing their work in those respective communities,” argued Dr Masoga.

“Power relations between the researcher and the communities involved in the research process should be clarified. The same applies to the ownership and control of knowledge generated and documented in a community.

“There is an increasing need for democratic and participatory development in our communities. This can be achieved by giving primacy to the interests, values and aspirations of the people at large. There must be a radical move from prevailing paradigm of development that suffers from relying on coercion and authoritarianism. There is a need to associate development with social needs. This will give validity and integrity to the local communities, thereby giving confidence to the leaders and their constituencies.”

Dr Masoga said that the time has come for African universities in particular to “de-emphasise factors that monopolise attention today. Factors like debt crisis, commodity prices and foreign investment, among others, must be replaced by emphasis on the regeneration of the grassroots. Many African universities and research institutions have not lived up to their responsibilities as guiding lights to the continent. However, all is not lost.

“The current global race for knowledge works against so-called developing countries, especially in Africa. There is a far greater need to have a code of ethics drawn up for researchers engaging with local communities, to ensure the promotion and protection of indigenous knowledge systems.”

Meanwhile, a cross-section of papers were also delivered during the symposium. These ranged from Moshoeshoe’s lessons in dealing with poverty alleviation as presented by Dr Samuel Mensah, Department of Economics, to indigenous grasses of Qwaqwa by Prof Rodney Moffett, Department of Plant Sciences. Also presenting lectures were Phephani Gumbi, African Languages; Tshele Moloi, School of Mathematics; Natural Sciences and Technology Education and Dr Tom Ashafa (Plant Sciences).

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