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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

Reaction by the Rector of the UFS after a meeting with student leaders
2008-02-25

Reaction by the Rector and Vice-Chancellor of the UFS, Prof. Frederick Fourie, on the agreement reached at a meeting with student leaders held on Friday, 22 February 2008

Note: This is meant to be used together with the full joint statement that was issued by the UFS management and student leaders on 22 February 2008.

The memorandum of the primes of the University of the Free State’s (UFS) residences was handed to top management on Wednesday, 20 February 2008. In the memorandum they asked for a meeting with the UFS management by Friday, 22 February 2008. Such a meeting was arranged and took place.

The UFS top management, all the residence primes as well as the house committee member for first years, the executive of the Main Campus Student Representative Council (SRC) and residence heads were present.

In contrast to what is suggested in the Volksblad report of Saturday, the discussion went off very well. There was no consternation or shouting or “emotions that ran high”. It was a civilised, decent meeting as it should be at a good university. Of course, now and again individuals spoke out strongly and very enthusiastically, but it was all decent and orderly. The contribution of the primes was insightful and well formulated.

Because the top management and I wanted to listen very carefully what the problems and frustrations were, we spent nearly five hours in the meeting. The issues in the memorandum were discussed one by one. In some cases I could take a decision immediately and finalise the matter, in other cases, the management provided information that could largely finalise a matter. A number of other matters must be investigated further.

The management undertook to respond comprehensively and in writing to all the issues raised in the memorandum by Monday, 25 February 2008. This will be handed to the primes but will not be handed to the media beforehand.
It is obvious that there are matters at the university that can be better managed and that there are problems with communication within the Student Affairs division. A major change such as the new policy on diversity places huge demands on management and the administration, and problems were to be expected. However, we understand the frustration of the students in residences.

On the other hand, students don’t always make matters easier. The strong opposition of white student leaders last year, and their unwillingness to co-operate in preparation for 2008 is well known. This year it is going better. But often student leaders take positions that are very inflexible. They also see no room for adapting old habits and simply want their own way. Their contributions are then full of statements such as “It cannot be done”. This delays measures such as the full implementation of expert interpreting services, which, for the management, is a very important measure (and which is functioning very well in certain residences). Communication from student leaders to management is also not always what it should be.

At the end of the meeting student leaders and management reached an important agreement and issued a joint statement in which they committed themselves to the integration process and to good co-operation and communication. This was an important step which is a sign of rebuilding trust. Naturally everyone will still have to work hard to build on this and to strengthen mutual trust.

The course and outcome of Friday’s discussions, as requested by the student leaders, show that issues can be addressed and resolved by means of us talking to one another. This is why it is so sad that primes and house committee members went on strike on Wednesday already and stayed in tents in front of the Main Building – leaving their residences without its leadership. This created an opening for what appears to have been well planned and co-ordinated acts of vandalism by inhabitants of residences on the campus on Wednesday.

Such vandalism is unacceptable and no one can justify it.

Fortunately, order could be restored quickly during the night and all academic activities could resume without any disruption on Thursday and Friday.

FCvN Fourie

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   
24 February 2008

 

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