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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

New Rector and Chancellor inaugurated at UFS

2003-02-07

NEW RECTOR AND CHANCELLOR INAUGURATED AT UFS

Newly inaugurated Rector and Vice-Chancellor of the University of the Free State, Prof Frederick Fourie, has recommitted the university to the service of the broader community, through the pursuit of academic excellence and contributing to building a non-racial, democratic and just South Africa.

To make this a reality Prof Fourie proposed a social contract or accord between university constituencies and the community to chart the way forward to establishing a university that can meet the challenges of a developing democracy.

Prof Fourie was speaking at his inauguration ceremony on the Bloemfontein campus, where the former Ambassador to the United States, Dr Franklin Sonn, was also inaugurated as Chancellor of the UFS.

The twin inauguration ceremony – the first in the history of the UFS - was attended by former President Nelson Mandela, Education Minister, Kader Asmal, Free State Premier Winki Direko, and the executive mayor of Mangaung, Mr Pappie Mokoena, who all endorsed the appointments as evidence of the transformation of the UFS.

According to Prof Fourie, the greatest contribution that any university could make to social and economic development in South Africa was by being an excellent university that encouraged critical inquiry, scientific knowledge as well as community service.

“So whilst we cherish and foster the continuity of the university as part of the ageold international tradition of universities, this University embraces its particular role in this country now, embraces the changes in the form and scope of its role in this crucial period of our history. We are committed to making a real difference to the new nation,” he said.

His vision for the UFS was “to be a university of excellence, equity and innovation – a leader in research, teaching, community service, adult learning, transformation, non-racialism, non-sexism, multi-culturality and multilingualism – a contributor to our country and our continent’s growth and development – a truly South African university”.

Prof Fourie said the recent incorporation of the Qwaqwa campus of the University of the North into the University of the Free State, which is the first such incorporation to take place, would contribute to broadening access for poor communities to higher education. Introducing an innovation to the inauguration ceremony, Prof Fourie and the UFS staff pledged to their commitment to excellence and justice, quality and equity. Fourie is the 13th Rector of the University of the Free State, succeeding Prof. Stef Coetzee, and Dr Sonn is the 6th Chancellor, succeeding Ms Winkie Direko, Premier of the Free State.

In his inaugural address, Dr Sonn said the significance of today’s ceremony was that the UFS - as a former institution of the Afrikaner – had chosen to walk the path of justice and not merely survival. “This university has seemingly liberated itself. It is inclusively South African.

He said the academic community must play its role of vigilance and not indifference”. Referring to the stature of former president Mandela in international affairs, Dr Sonn said: “We must bring the weight ot science and critical analysis and interpretation to bear in support of Madiba and other moral giants.”

Inauguration Speech by Prof. Frederick C.v.N. Fourie (PDF format)

Inauguration Speech by Dr Franklin A. Sonn (PDF format)

Statement by the Minister of Education, Professor Kader Asmal (PDF format)

Speech by Prof. Viljoen (PDF format)

Speech by Executive Mayor Mokoena - Mangaung Local Municipality (PDF format)

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