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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 honours its sport stars
2008-10-24

 

The UFS's sport stars are, from the left: Robert Ebersohn, junior mens sport star, Boy Soke, Sportsman of the Year, and Mari-Lise Linde, junior women sport star. Adéle Niemand, Sportswoman of the Year, was absent.

 The University of the Free State (UFS) this week honoured its sport stars during the annual Kovsie Sports Dinner, held in Bloemfontein.

Boy Soke, long distance runner who has obtained national colours in all three disciplines of athletics was named Sportsman of the Year. Protea netball player Adéle Niemand was named Sportswoman of the Year for the second consecutive year.

The Cheetah and Springbok sevens rugby player, Robert Ebersohn and netball player Mari-Lise Linde were named junior sport stars.

“The inclusion of five of our students in the South African team that took part in the Beijing Olympic Games is an indication of the standard of sport at the university. We are proud of all our sportsmen and women and salute them for the effort they put in to achieving their goals,” said Mr James Letuka, Director of KovsieSport.

The UFS this year had several other achievements, namely: The inclusion of eight Free State cricket players in the amateur team, the hockey team winning the University Sport South Africa (USSA) B section, the inclusion of three soccer players in the USSA team, rugby winning the USSA competition for the second time, netball winning gold on the USSA tournament for the fourth consecutive year, and the ladies tennis winning the USSA tournament.

The following awards were also made in the university’s different sporting codes during the Kovsie Sports Dinner:

Roné Reyneke: Athletics
Boy Soke: Athletics
Murray Capon: Hockey
Cherie Smith: Hockey
Doretha Joubert: Netball
Riaan Jordaan: Cricket
Wayne Stevens: Rugby
Karin Coetzee: Tennis
Willem Steenkamp: Tennis
Gabisele Hlumbane: Soccer
Lehlohonolo Mofokeng: Soccer
Prof. Martin Dednam: Devoted service to badminton
Sarah Shannon: Special merit award for participating in the Paralympics Games in Beijing

The guest speaker was Dr Derik Coetzee who was the head of Springbok Rugby Team’s conditioning during last year’s Rugby World Cup.

Media Release
Issued by: Lacea Loader
Assistant Director: Media Liaison
Tel: 051 401 2584
Cell: 083 645 2454
E-mail: loaderl.stg@ufs.ac.za  
23 October 2008
 

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