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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

2015 RAG promises family fun
2015-01-30

The annual Kovsie Rag Community Service (CS) procession will take place on Saturday 31 January 2015 and this year’s theme is all about Video Games and City Icons.

The floats are judged on  31 January andwill depart at 09:00 from the UFS Bloemfontein Campus’ Furstenburg Gate (near Tempe) for the first procession of the day.

Their route will end at Twin City mall where 6 000 meals will be distributed to Heidedal and Mangaung communities.

The float winners will be announced at 17:00, just before the main procession of the day will again depart from Furstenberg Gate in Nelson Mandela Drive.The 2014 UFS Rag queen, Mr Rag and their runners-up will greet the public from the main float. Finalists for the 2015 UFS Rag queen and Mr Rag titles will also accompany the procession.

The popular family festival will take place at Chevrolet Park cricket stadium. There, young and old will be entertained by well-known artists such as K. O, Riana Nel and Matthew Mole.

Do not miss out on this wonderful family festival – come early, bring your family and picnic blanket/chairs to ensure a great spot on the grass. A variety of refreshments will be on sale.

Tickets are available from Computicket as well as at the entrance gates.
Tickets: R80 per person
R50 per child under 12

KFC Rag Procession 31 January 2015 Programme:

09:00 floats depart from the university at the Furstenburg gate
11:00 procession and floats arrive at Twin City Mall in Heidedal
11:00 – 12:00 Westline Aviation air show; distribution of food parcels and balloons released
16:00 Chevrolet Park cricket stadium gates open
18:00 procession and floats depart from the university to Chevrolet Park via Nelson Mandela drive
19:00 – 20:00  Riana Nel
20:00 – 20:45 procession and floats arrive at Chevrolet Park
20:45 – 21:45  Matthew Mole
22:00 – 23:00  K. O

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