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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

Forensic investigation at UFS Computer Services division in final stage of finalisation
2007-02-01

Statement by prof Niel Viljoen, Chief Director: Operations  
 
The case in which possible irregularities were investigated at the University of the Free State’s (UFS) Computer Services Division at the end of 2005, and which led to two Deputy Directors’ compulsory leave pending an investigation, is making good progress and is in the final stage of finalisation.
 
One of the Deputy Directors resigned unconditionally a day before his disciplinary hearing was to take place. He is one of two staff members who were placed on compulsory leave after an internal investigation ordered by the UFS management indicated possible irregularities in the division.
 
“As a result of the extent of the case and the involvement of more than one local business, the investigation had a long course,” said Prof Viljoen.
 
“The Deputy Director who resigned would have appeared before a disciplinary committee with Judge Joos Hefer as chairperson on charges of misconduct, involving more than R500 000,” said Prof Viljoen.
 
“We are going ahead with the process of criminal prosecution against this person and a docket was opened at the commerce branch of the South African Police Services (SAPS).  A civil action to recover damages from him was started,” Prof Viljoen said.
 
With a couple of exceptions, the internal disciplinary process of the other persons involved in the case is also finalised. “The disciplinary hearing of the Deputy Director, who is still in the service of the UFS’s Computer Services division, is scheduled for May 2007. This person is still on compulsory leave,” Prof Viljoen said.
 
“To demonstrate our commitment to the enhancement of honest work ethics and to give to personnel and students a mechanism to bring any unethical business practices to the attention of the UFS management, a fraud hotline was installed last year. The hotline is operated 24 hours a day for 365 days of the year by KPMG,” Prof Viljoen said.
 
Prof Viljoen thanked everyone who was involved in the investigation for their cooperation. This includes staff as well as people from outside the UFS.  “We are committed to transparent corporate management. Any possible irregularities will be investigated and if staff or students are found guilty of any irregular behaviour, strict actions would be taken against these persons,” Prof Viljoen said.
 
Media release
Issued by: Lacea Loader
Media Representative
Tel: (051) 401-2584
Cell: 083 645 2454
E-mail: loaderl@mail.ufs.ac.za
2 February 2007
 

 

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