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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

Report card outlines major achievements
2005-02-04

Staff at the University of the Free State (UFS) have received above-inflation increases in remuneration averaging 18,2 percent since the year 2000, according to the Rector and Vice-Chancellor, Prof Frederick Fourie.

Delivering a keynote speech at the Official Opening of the UFS today, Prof Fourie gave a report card for the UFS which he said indicated significant progress in salaries and promotions as well as capital expenditure and infrastructure development on the campus.

“The aggregate extra earnings of staff (money in their pockets above inflation) from 2000 to 2005 amount to R75 million in salaries. This is the result of the hard work of all staff and we pay tribute to them,” he said.

Prof Fourie said that several categories of staff are better off than before the financial turn-around strategy was implemented in 2000 which aimed to make the UFS a financially sustainable campus.

The lowest paid workers and professors had received an additional structural correction, which gave professors at the UFS a 27% above-inflation increase (on total remuneration package) since 2000.

He said there had also been a dramatic increase in promotions to associate professor and full professor during the last 6 years.

From 1999 to December 2001, there were only 9 promotions to associate professor. From January 2002 to January 2005, there were 37 such promotions to associate professor, four times as many.

Regarding promotions to full professor, from 1999 to December 2001 there were 7 promotions. From January 2002 to January 2005, there were 31 promotions to full professor, more than four times as many.

“We have also created a new category of senior professor to give due recognition to the outstanding work of our leading academics in many fields,” Prof Fourie said.

The UFS has introduced numerous new and innovative learning programmes, together with an increasing number of community service modules which enhanced the UFS as a leader in service learning and helped to make it a university engaged with its surrounding community.

According to Prof Fourie the number of support staff had also grown along with the professionalisation of the support services.

He said management was aware that there still several challenges regarding staff overload and staff development but that these were being addressed

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

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