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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 responds to media reports about UFS101
2012-08-18

The UFS101 is a cross-disciplinary module of the University of the Free State (UFS) that encourages critical thinking and offers access to knowledge beyond the specific qualifications for which students are registered. This is a multi-disciplinary academic curriculum that includes topics in astronomy, nanotechnology, history, law, anthropology and religion.

Throughout the seven units students are taught to think broadly rather than narrowly, and critically rather than through rote-learning.

The core curriculum module raises some difficult questions about science, humanity and the universe that have occupied human beings for centuries. There is considerable effort put into the module to enable balance, respect, and independent thinking. Students are not taught what to think but are offered different perspectives on difficult issues.

“In my unit on the question ‘how should we deal with the past?’ every effort is made for students to examine the perspectives on history held by people from different communities in South Africa,” said Prof. Jonathan Jansen, Vice-Chancellor and Rector of the UFS.

Students are then encouraged to speak in class, online and in tutorial groups where they are given ample opportunities to take a position and defend it not through emotion and anger, but through logic and reason.

The objective of the module is to equip students to deal with “the present past” in constructive and empathetic ways. They are also prepared to become active citizens outside the classroom and gain skills they can use anywhere in the world.

Some students find the module difficult at first, since most of them are not used to the practice of critical thinking and dealing with difficult questions from the past, the present and the future. Most students gradually come to enjoy the core curriculum module as they become accustomed to a new style of teaching and learning.

There are 700 first-year modules at the UFS. This is the only one module offered to students in English so that all students, local and international, can engage with one another directly on the subject matter discussed in the module. However, the module material is also available in Afrikaans online.It is a pity that AfriForum Jeug Kovsies did not discuss their concerns with the presenters of the module, but chose to do it through the media.

It is a pity that AfriForum Jeug Kovsies did not discuss their concerns with the presenters of the module, but chose to do it through the media.

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