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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 Spring Graduation Ceremony rekindles spirit of Ubuntu
2015-09-22

 

Our graduates: A new generation of future leaders
to advance South Africa

 -  Video: Spring Graduation Ceremony

“Give away your love, attention, care and more.” These words of Prof Jonathan Jansen, Vice-Chancellor and Rector of the University of the Free State (UFS), capture the spirit of the 2015 Spring Graduation Ceremony that took place on Thursday 17 September 2015.

On this special day, 599 diplomas and degrees were conferred from the faculties of the Humanities, Education, Law, Theology, Economic and Management -, Health -, and Natural and Agricultural Sciences. Central to both the morning and afternoon ceremonies was the message of Ubuntu.

The essence of humanity

“Here is my advice to you,” Prof Jansen said to the graduates, “whatever you have, give it away. Give away your love, attention, care and more.” Prof Jeffrey Sachs, guest speaker at both events, supported this message by saying that the essence of humanity is the cornerstone to success. Prof Sachs, a prominent American economist and humanitarian, asked graduates to use their hard-earned knowledge wisely, fairly and boldly. “You are the wealth of South Africa, for your knowledge is the key to SA’s prosperity.”

The UFS Faculty of Economic and Management Sciences honoured Prof Sachs by conferring an honorary doctorate on him. With this prestigious conferral, the faculty acknowledges Prof Sach’s extensive work in sustainable economic, social and political development across the globe. Dr Khotso Mokhele, Chancellor of the UFS, commended Prof Sachs for his compassion and passion for humanity. “I’m truly inspired that you agreed to associate yourself with this institution. We are proud to be associated with your excellence,” Dr Mokhele said.

Celebrating the extraordinary

One of many highlights of the day was when Leanne Kunz and Karabo Motlhakoana walked across the stage to respectively receive their Postgraduate Diploma in Business Administration and a BSc degree in Information Technology.

Kunz has been compiling news bulletins for The Breakfast Special show, aired on the OFM radio station, for five years. This Kovsie Alumnus graduated with a Media Studies degree a few years ago. Kunz did not allow her successful career at the popular radio station to hinder her studying further, though. Neither has Motlhakoana’s physical challenges.

While everyone else used their hands to take notes, Motlhakoana used his foot. Despite being born with no arms, he was able to beat the odds by qualifying as a computer scientist. Motlhakoana was also involved in the Leadership for Change programme in 2011 which contributed to producing the well-rounded graduate he is today. When walking across the stage, “I felt like I achieved something that gave me a challenge,” he said.

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