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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

New violinist for Odeion String Quartet
2013-02-06

Samson Diamond
06 February 2013



The Odeion String Quartet has a new member, a young accomplished violinist with a string of awards to his name. Samson Diamond, who won the Standard Bank Young Artist Award for Music in 2010, has joined the quartet. He is the first male member the quartet has had for about five years. The Soweto-born violinist replaced Denise Sutton, former leader and first violinist. He will lead the quartet, a flagship of the university and the only resident string quartet at a South African university. The other three members are Sharon de Kock (violin), Jeanne-Louise Moolman (viola) and Anmari van der Westhuizen (cello).

Twenty-eight year old Diamond, a graduate of the Royal Northern College of Music in Manchester, UK, says he is looking forward to working with students from the Odeion School of Music. “I am sure there are many talented students here.”

The musician, who obtained both his Bachelor of Music Honours degree and his Masters of Music Performance degree with distinction, will be based in Bloemfontein on a full time basis. As a member of the quartet, he will be giving concerts, coaching chamber music for the various chamber ensembles and will also give individual lessons to some of the violin students at the School.

Diamond, who started playing the violin at age ten, boast a long list of achievements. At age 12, he was leader of the Buskaid Soweto String Ensemble, one of the country's prominent youth projects. He was a founding member of the jazz classical band Quattro Fusion and former leader of the Diamond quartet. He has performed before many distinguished guests, including Queen Elizabeth II, the Duke of Edinburgh and former presidents Nelson Mandela and Thabo Mbeki.

Diamond says being the first male member in years will not bring about a change in the quartet He says it is about the standard of playing and the calibre of music.

“Music is music whether you work with men or women.”

Diamond’s first performance as member of the quartet will be on 21 February 2013. Details about the performance will be communicated later.

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