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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

Student rights revived
2015-03-30

Lindokuhle Ntuli fulfils his promises.

“I can assure you that each and every promise that I’ve made to the students will be fulfilled.”

That is a promise that Lindokuhle Ntuli, SRC Legal and Constitutional Affairs (Bloemfontein Campus) gave to Kovsie students. The fourth-year LLB student and founder of the UFS Legal Behemoth describes himself as an ambitious person with a passion for law, order, and formality.

He explains the duties of his portfolio as “the office that will really ensure that the interests of all students are catered for. That student’s consumer rights are respected and not violated.” Through his portfolio, he aims to make sure that students are aware of what their rights are.

As part of his portfolio, Ntuli has re-introduced the Student Court, which will be fully functional during the second semester. The portfolio also introduced the Student Engagement Forum.  The purpose of the forum is for students to share their grievances with regards to student rights violations. These discussions will take place twice a semester.

“The student engagement forum is the means by which we are able to really assess what kind of rights of the students are being violated,” Ntuli added.

Together with Louzanne Coetzee, SRC Accessibility and Student Support, Ntuli aims to establish the Student Rights Desk. The desk will deal directly with student rights on campus without recourse to the student court or external courts.

When asked about what his vision for the SRC is, Ntuli responded:

“My vision for the SRC is to see the SRC really attending to each and every need of students. We must advocate for students in the best way we can.”

And the words Lindokuhle lives by?

“Law and order exist for the purpose of establishing justice, and when they fail in this purpose, they become the dangerously structured dams that block the flow of progress” (Martin Luther King Jnr).

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