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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

Department celebrates 50th anniversary
2009-03-25

 
The first Departmental Head and the subsequent Departmental Chairpersons at the dinner on 14 March this year. From left: Proff Bernard Prior (1991-1998), Piet Lategan (1962-1990), Derek Litthauer (1998-2002) and James du Preez (2002-). These are all the Heads/Chairpersons of the Department since its founding in 1959, with the exception of Prof Hans Potgieter who acted as Head during 1959-1962.
Photo: Stephen Collett
 
Department celebrates 50th anniversary

On 13 March the Department Microbial, Biochemical and Food Biotechnology at the University of the Free State (UFS) celebrated its 50th anniversary in a splendid fashion with a lecture entitled, The origin of life: Exactly how did life begin? as part of the Darwin commemorative lecture series, followed by a reunion of current and former staff members and postgraduate students of the department with a barbeque on the following day.

The proceedings were concluded on 14 March with a gala dinner in die Centenary Complex at the UFS attended by 153 staff members, post-graduate students (current and former) and other guests. During the dinner the guests were treated to a presentation of historical photos of the founding and development of the department. Currently the department is one of the largest departments in the Faculty of Natural and Agricultural Sciences in respect of the number of staff members and students as well as research outputs. This is the result of entrepreneurial actions to increase student numbers and research activities, as well as the merging with the smaller Department of Biochemistry in 1988 and more recently with the Department of Food Science in 2002. The department comprises 20 academics, 24 support staff and 65 postgraduate students. It also boasts 12 lecturers with ratings from the National Research Foundation (NRF), which include three academics with a B-rating, an indication of international recognition for their research. The department has the largest number of lecturers with an NRF-rating at the UFS. 

“It was interesting to learn during the reunion of the variety of professions occupied by former students of the department, i.e. at other tertiary educational institutions, the CSSIR, SAPPI, Sasol and a multitude of other industries, as well as at research institutions in the USA and Australia,” said Prof. James du Preez, Head of the Department.

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