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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

Staff, students, learners and the public opened their hearts during R5 coin-laying ceremony
2012-07-17

Photo:  Sonia Small
18 July 2012

Amidst a festive atmosphere on the Red Square in front of the Main Building on the Bloemfontein Campus of the University of the Free State (UFS), students, staff, learners and members of the public came together to make their contribution to stop hunger.

In celebration of former president Nelson Mandela’s birthday, the university collected money and food in the form of a coin-laying ceremony, the packing of food parcels, and a message delivered by Emeritus Archbishop Desmond Tutu in aid of the university’s No Student Hungry (NSH) campaign and Bloemfontein Child Welfare.

Representatives from schools in Bloemfontein donated their R5 coins, together with university staff, students, members of the public, and employees of Pick n Pay Hyper. Money collected at the coin-laying ceremony will be shared between NSH and Bloemfontein Child Welfare.

According to Ms Grace Jansen and Ms Carin Buys, patrons of NSH, the more than R42 000 that was collected will be donated to Bloemfontein Child Welfare in an effort by NSH to give back to the community. “We are impressed by the number of people who showed up and by the fact that people opened their hearts and pockets to give,” said Ms Buys.

Thirty employees of Pick n Pay Hyper in Bloemfontein were also present and packed 1 833 food parcels (equivalent to 11 000 meals). This forms part of a Pick n Pay initiative in cooperation with Stop Hunger Now that is being held countrywide today.

In total, 88 000 meals will be distributed in six cities in South Africa today. The 11 000 meals in the Free State have been donated to the university and according to Ms Jansen a social worker at the UFS will distribute it to other needy students. These are students who do not receive bursaries from NSH at the moment. Every food parcel contains rice, dried vegetables, soya, and vitamin and mineral enriched powder.

The university was honoured to have Emeritus Archbishop Desmond Tutu as the speaker at the event. He attended a dialogue in the Series of Dialogue between Science and Society today at the university where he took part in a conversation with Profs. Mark Solms and Pumla Gobodo-Madikizela as part of the Global Leadership Summit.

He made a special appearance at the university’s Nelson Mandela Day festivities. His message was simple but inspiring: “Everyone has, just like Madiba, the capacity to change lives. I hope there are people present who can say that they want to improve someone else’s life. You have the chance to make South Africa a country where no one goes to bed hungry. Help us to make South Africa a country where we have compassion for each other and care for each other”.

The UFS would like to thank the following schools for their contributions: 

Grey Kollege Primêre Skool
Grey Kollege
St Michael's School for Girls
Hoërskool Jim Fouché
Hoërskool Fichardtpark
Hoërskool Sentraal
Navalsig High School
HTS Louis Botha
Eunice High School 


 

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