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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

Student gives hope to childhood cancer patients
2015-10-16


Siphokuhle Jama believes that the underprivileged are also destined to reign.

The inaugural ‘Dance and Musical Childhood Cancer Fundraising Day’, held on Saturday 26 September 2015 at the Free State Childhood Cancer (CHOC) Foundation, was “a huge success,” according to Siphokuhle Jama, the organiser.

Siphokuhle is a second-year BSc Agricultural Economics student at the University of the Free State (UFS), who has devoted his life to bettering the lives of the less fortunate. The 21-year-old self-proclaimed motivational speaker, entrepreneur, and budding author was inspired by his humble beginnings to found the Destined to Reign Foundation, which champions various community initiatives in both his home town of Mtata and Bloemfontein.

To support the fight against childhood cancer, the young philanthropist took it upon himself to invite music and dance fanatics either to perform or to enjoy spectatorship for a good cause. The impressive support received from the UFS, Universitas Academic Hospital, and Central University of Technology (CUT), various artists, and the community has contributed towards ensuring that the inaugural fundraiser was a prelude to annual events to come.

Singers, dancers, and poets entertained the audience with vigour, making the day one of the most special for the young children, who spend their days and nights at the CHOC House, with little to do but undergo radiation and chemotherapy and await a discharge date. .

All proceeds went towards basic needs, such as food, toiletries, and clothing for the children residing at the House, which is located in the same suburb as our university. In addition to accommodating dozens of cancer patients and their mothers, the House also assists with the treatment and rehabilitation of children suffering from life-threatening blood disorders. Thus, the fundraiser served to promote awareness of these health conditions.

Siphokuhle’s passion for giving hope to the underprivileged was unveiled by a school community engagement project 14 years ago. He has never looked back.“It has always been in my heart to serve my community,” he said.

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