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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 many during Autumn diploma and graduation ceremony
2007-04-16

The University of the Free State (UFS) will award 797 diplomas and 2 633 degrees from 23-26 April 2006 during this year’s autumn diploma and graduation ceremony. Students from the Main Campus and Vista Campus will take part in the ceremony.   
 
Altogether 32 doctorates and two honorary doctorates will be awarded. The honorary doctorandi are Prof. Barend Johannes (Bannie) Britz and author Mr Khotso Pieter David Maphalla. 
 
On 26 April 2007 Prof. Britz will be honoured for his contribution to architecture when the degree D.Arch. (h.c.) will be awarded to him.
 
Mr Maphalla will be honoured for his contribution to the development of the Sesotho language and culture. He will receive the degree Ph.D. (h.c.) on 12 May 2007 during the graduation ceremony of the Qwaqwa Campus.
 
On 23 April 2007 at 08:30 altogether 497 diplomas will be awarded in the upgrading programmes of the School of Education in the Faculty of The Humanities, namely A.C.E, N.P.D.E. and C.E. At 14:30 on the same day 300 diplomas will be awarded to students from all the faculties.
 
On 24 April 2007 at 08:30 altogether 442 degrees and three doctorates will be awarded in the School of Education and at 14:30, 461 degrees and four doctorates will be awarded in the Faculty of The Humanities, excluding the School of Education.  
 
On 25 April 2007 at 08:30 altogether 296 degrees and one doctorate will be awarded to students in the Faculty of Economic and Management Sciences. This includes students in B.Acc., B.Admin., B.Pub., related honours degrees and all masters and doctors degrees. At 14:30 on the same day degrees will be awarded to 482 students from the Faculty of Economic and Management Sciences, excluding students in B.Acc., B.Admin., B.Pub., related honours degrees and all masters and doctors degrees.
 
On 26 April 2007 at 08:30 altogether 595 degrees, 19 doctorates and one honorary doctorate will be awarded in the Faculty of Natural and Agricultural Sciences. At 14:30 on the same day 357 degrees and five doctorates will be awarded to students in the Faculties of Health Sciences, Law and Theology.
 
Both the diploma and degree ceremonies will be held in the Callie Human Centre on the Main Campus in Bloemfontein.
 
Media release
Issued by: Lacea Loader
Assistant Director: Media Liaison
Tel: 051 401 2584
Cell: 083 645 2454
E-mail: loaderl@ufs.ac.za
16 April 2007

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