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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

Migration is a developmental issue - experts
2010-06-01

Pictured from the left, front, are: D. Juma, Mr Williams and Prof. Hussein Solomon (University of Pretoria); back: Prof. Bekker, Prof. Lucius Botes (Dean: Faculty of the Humanities, UFS) and Dr Wa Kabwe-Segatti.
Photo: Stephen Collett


“Migration offers more opportunities for economic growth than constraints. It is an integral part of the processes of globalisation and regional integration.”

This was a view shared by one of the speakers, Dr Monica Juma from the Africa Institute of South Africa, during a panel discussion hosted by the Centre for Africa Studies (CAS) at the University of the Free State (UFS) last week as part of the celebrations of Africa Day on 25 May 2010.

The discussion was premised on the theme, Migration and Africa: From Analysis to Action.

Dr Juma said migrants could be assets for host countries or cities because of their resourcefulness. She said they brought along essential skills that could contribute immensely to the economic development of their host countries or cities.

“Governments are beginning to see migration as a tool for development and working together in developing immigration policies,” concurred another speaker, Mr Vincent Williams from the Institute for Democracy in South Africa (IDASA).

He said, if managed properly, migration could yield positive results. He said effective management of migration should start at local and provincial levels.
And for this to happen, he said, the current immigration laws should be amended as he felt they were no longer relevant, because they were based on what countries wanted to achieve in the past.

“Reform national immigration legislation to encourage permanent settlement and improve service delivery mechanisms and bureaucracy to match population movements,” Dr Aurelia Kazadi Wa Kabwe-Segatti, from the Forced Migration Studies Programme at the University of the Witwatersrand recommended.

However, Mr Williams pointed out that policy convergence was a difficult thing to achieve as migration was a politically sensitive issue. He said decisions that countries made on migration could have a negative or a positive bearing on their relations with one another.

Dr Juma also raised the issue of unskilled migrants which, she said, could be a burden to governments. This was reflected in the current South African situation where foreigners offered cheap labour and thus rendered South Africans who demanded higher salaries unemployable. This was a contributory factor to the xenophobic attacks of 2008. What was essentially a labour problem then manifested itself as a migration problem.

Prof. Simon Bekker from the University of Stellenbosch said South Africa was still losing a significant number of skilled professionals to Europe and North America due to an assumption that spatial mobility led to social or economic mobility.

He also suggested that the government should not restrict internal migration but should address the problem of migration across the borders into South Africa.

Senior Professor at the CAS, Prof. Kwandiwe Kondlo, said while the discussion covered a broad scope, there were some gaps that still needed to be filled in order for an all-inclusive view to prevail. One such gap, he said, was to also accord indigenous traditional institutions of governance space in such deliberations and not base discussions on this issue only on the Western way of thinking.

Africa Day is the day on which Africa observes the creation of the Organisation of African Unity (OAU) on 25 May 1963, to promote the unity and solidarity of African states and act as a collective voice for the African continent; to secure Africa’s long-term economic and political future; and to rid the continent of all remaining forms of colonialism. The OAU was formally replaced by the African Union in July 2002.

Media Release
Issued by: Mangaliso Radebe
Assistant Director: Media Liaison
Tel: 051 401 2828
Cell: 078 460 3320
E-mail: radebemt@ufs.ac.za  
1 June 2010
 

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