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TED Talks about rainbows

18 April 2022 | Story Leonie Bolleurs | Photo Stephen Collett

“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 boasts with most advanced chemical research apparatus in Africa

2005-11-23

Celebrating the inauguration of the NMR were from the left Prof Frederick Fourie (Rector and Vice-Chancellor of the UFS), Dr Detlef Müller (Development Scientist and Manager: Africa and Asia of Bruker in Germany, the supplier of the NMR), Prof Jannie Swarts (head of the head of the Division Physical Chemistry at the UFS) and Prof Herman van Schalkwyk (Dean: Faculty of Natural and Agricultural Sciences at the UFS). Photo: Lacea Loader

UFS boasts with most advanced chemical research apparatus in Africa

The University of the Free State’s (UFS) Department of Chemistry now boasts with some of the most advanced chemical research apparatus in Africa after the latest addition, a nuclear magnetic resonance (NMR) spectrometer, was inaugurated today by the Rector and Vice-Chancellor, Prof Frederick Fourie. The NMR is used to analyse molecular structures.

Last month the Department of Chemistry celebrated the installation of the most advanced single crystal X-ray diffractometer in Africa. The diffractometer provides an indispensable technique to investigate among others the solid state of compounds for medicinal application.

“Three years ago the UFS executive management realised that, if we want to build a university of excellence, we should invest in research. We started to think strategically about chemistry and decided to bring the apparatus at the Department of Chemistry on a more competitive standard. Strategic partnerships were therefore secured with companies like Sasol,” said Prof Fourie during the inauguration ceremony.

“The installation of the NMR symbolises the ability of the UFS to turn academic areas around. I hope that this is the beginning of a decade of excellence for chemistry at the UFS,” said Prof Fourie.

”The catalogue value of the Bruker 600 MHz NMR is approximately R11 million. With such an advanced apparatus we are now able to train much more post-graduate students,“ said Prof Jannie Swarts, head of the Division Physical Chemistry at the UFS.

”The NMR is the flagship apparatus of the UFS Department of Chemistry that enables chemists to look at compounds more easily at a molecular level. Research in chemistry is critically dependent on NMR, which is a technique that can determine the composition of reactants and products in complicated chemical reactions, with direct application is most focus areas in chemistry,“ said Prof Swarts.

”Parts of the spectrometer consists of non-commercial items that were specifically designed for the UFS Department of Chemistry to allow the study of unique interactions in e.g. rhodium and platinum compounds,” said Prof Swarts.

According to Prof Swarts the NMR enables chemists to conduct investigations on the following:

To evaluate for example the complex behaviour of DNA in proteins as well as the analysis of illegal drugs sometimes used by athletes.
It provides an indispensable technique to investigate compounds for medicinal application for example in breast, prostate and related bone cancer identification and therapy, which are currently synthesised in the Department of Chemistry.
It can also be applied to the area of homogeneous catalysis where new and improved compounds for industrial application are synthesized and characterised, whereby Sasol and even the international petrochemical industry could benefit. This analytical capacity is highly rated, especially in the current climate of increased oil prices.
The NMR can detect and identify small concentrations of impurities in feed streams in the petrochemical industry, e.g. at Sasol and also the international petrochemical industry. These minute amounts of impurities can result in metal catalyst deactivation or decomposition and can cause million of rands worth in product losses.
It is indispensable for studying the complexity of samples that is non-crystalline. These materials represent the vast majority of chemical compounds such as solvents, gasoline, cooking oil, cleaning agents and colorants as examples.

According to Prof Swarts the general medical technique of MRI (magnetic resonance imaging) in use at larger hospitals, is based on NMR technology.

”The NMR apparatus enabled the Department of Chemistry to characterise complex molecules that were synthesised for the multi-national company, FARMOFS-PAREXEL, and to negotiate research agreements with overseas universities,” said Prof Swarts.

Media release
Issued by: Lacea Loader
Media Representative
Tel: (051) 401-2584
Cell: 083 645 2454
E-mail: loaderl.stg@mail.uovs.ac.za
22 November 2005

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