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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

Schoolgirl builds giant Gingerbread house for Children’s Wing Project
2015-11-13


Professor André Venter, Head: Department of Paediatrics and Child Health, Morgan Pelser, and Tertia de Bruin, Project Coordinator: Children’s Wing: UFS Marketing.
Photo: Leonie Bolleurs.

“You have to dream before your dreams can come true.” These words rang true for Morgan Pelser from Bloemfontein when she fulfilled her wish on Tuesday 3 November 2015 at the launch of her ‘big and real’ Gingerbread house.

 

Pelser, 13, said she had the idea of building the gingerbread house over six months ago and began working tirelessly, raising funds for the project. She intends to donate the money raised from this initiative to the Children’s Wing Project at Pelonomi and Universitas Hospitals. It was back in Grade 4 when she had the opportunity to tour through the ICU, neonatal and paediatric wards of the two hospitals, that she saw the need for better equipment and facilities. Pelser hopes to raise R200 000 through the initiative.

 

Professor André Venter, Head: Department of Paediatrics and Child Health at the University of the Free State, said he was greatly humbled by the perseverance and passion shown by Morgan in executing her dream. “I work with children, so I know how resilient they are, but seeing this is amazing. We tend to give up so easily,” he said. He went on to say that the money will be greatly appreciated, as it will be used to provide health-care facilities for children at both hospitals.

 

The launch of the gingerbread house was a huge success. The house is currently outside Coco C at the Loch Logan Waterfront. Members of the public are encouraged to see and taste the giant house, where they can leave a message on the inside of the house. A minimum fee of R20 is requested.

 

Professor André Venter, Head: Department of Paediatrics and Child Health, Morgan Pelser, and Tertia de Bruin, Project Coordinator: Children’s Wing: UFS-Marketing.

Photo: Leonie Bolleurs.

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