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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

The Great Pool of Exhilaration
2015-02-11

Photo: Albert van Biljon 

 

Boys’ roars and ladies’ shouts could be heard from miles away. From this, one could tell that the 2015 first-year’s Swimming Gala was bound to be an exciting one.

While RC Sports members were stressing, the first-years blissfully continued in song and excitement.

One would think that, after a hectic first week of classes, first-years would not have much energy left, but the atmosphere proved that Residence Committees (RCs) had prepared the individuals with rather motivating pep talks before the event. Most male residences put their best foot forward, not holding back on themed attire and additional instruments, while female residences sang and danced to the music provided. Not only were the masses competing to claim that they had the greatest spirit on this night, but they were also waiting to hear the results of the Spirit Cup for the first-years’ Athletics, which was cut short due to heavy rain showers. This simply added to the already intense anticipation of first-years and RC Sports members, as they would receive the results only at the end of the event.

The competition was tough as many of the first-years who competed moved with ease in the water as though it was second nature to them. This year’s gala saw quite a few talented, national swimmers competing, which left those who swam for pride and points intimidated. The excitement of the crowd was heightened as the relay section of the programme approached. This meant that the winners were to be announced soon.

In the ladies’ section, the residences were placed:
• 1st – Marjolein
• 2nd – Wag-‘n-Bietjie
• 3rd – Sonnedou

In the men’s section, the residences were placed:
• 1st – Armentum
• 2nd – Vishuis
• 3rd – Karee

When the time arrived for the announcement of the Spirit Cup winners, many were hopefully clenching their hearts for their name to be roared out. In most people’s opinion, it came as no surprise when Armentum walked away with the Spirit Cup for both the first-years’ Athletics and the Swimming Gala. Furthermore, Armentum’s broader South College community – of which Emily Hobhouse, Marjolein, NJ vd Merwe and Villa Bravado are also part – walked away with the cash prize for the best mascot.

By end of the night, everyone, no matter if they were drenched or dry, experienced the exciting sporting atmosphere at Kovsies that they’ve now become a part of.

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