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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

Protection of Information bill- opinions from our experts
2011-11-28

Prof. Hussein Solomon
Senior Professor in the Department of Political Science at the University of the Free State. 

In recent years, given their failure to effectively govern, the ANC has become increasingly defensive. These defensive traits have become particularly acute in light of the various corruption scandals that members of the ruling party involve themselves in.
 
Given the fact that for now they are assured of an electoral majority (largely on account of their anti-apartheid credentials), coupled with the fact that they have managed to make parliament a rubber stamp of the executive as opposed to holding the executive accountable, it is the media which has increasingly held the ruling party to account by exposing such corruption and incompetence in government.
 
The passing of the information bill, therefore, is not merely an attack on the media, but an attack on the pivotal issue of accountability. Without accountability, there can be no democracy.
 
By defining national interest broadly, by refusing to accept a public interest clause in the bill, the ANC increasingly shows its disdain to South Africa's constitution and its citizens.
 
More importantly, as former Minister of Intelligence and ANC stalwart Ronnie Kasrils pointedly makes clear, the ANC is also betraying its own noble struggle against the odious apartheid regime. It was the media which played a key role in exposing apartheid's excesses, it is the same media which is coming under attack by the heirs of PW Botha's State Security Council - Minister of State Security Siyabong Cwele and his security apparatchiks whose mindsets reflect more Stalin's Gulag's than the values of the Freedom Charter.
 
The passing of this bill is also taking place at a time when journalists have had their phones attacked, where the judiciary has been deliberately undermined and parliament silenced.
 
Democrats beware!

 
Prof. Johann de Wet
Chairperson: Department of Communication Science 
 
The ANC’s insistence on passing the Protection of State Information Bill in its current form and enforcing it by law, means that the essence of our democratic state and the quality of life of every citizen is at stake.
 
Yes, our freedom as academics, researchers, mass media practitioners and citizens comes into play. Freedom implies the right to choose and is, along with equality, an underlying principle which helps make democracy happen. While the South African state needs to protect (classify) information which could threaten its security and/or survival, the omission of a public interest clause in the Bill at this stage effectively denies a citizen the right to freedom of information.
 
 Freedom of information, along with press freedom, freedom of speech, freedom of assembly, freedom of association and religious freedom, are essential to democracy. These freedoms are granted because they conform to basic liberal ideas associated with (Western) democracy and which resonate with South Africa’s liberal constitution, such as (1) belief in the supreme value of the individual (and thus not of the state); (2) belief that the individual has natural rights (rights which belong to all human beings by nature – such as the right to life and to control government)) which exist independently of government, and which ought to be protected by and against government; and (3) recognition of the supreme value of the individual. 
 
One wonders how many cases of South African government corruption and mismanagement would have been uncovered by investigative journalists over the past number of years if this Bill in its current form was on the statute books. This Bill represents a backward step from the promise of democracy of having an informed public. The former National Party government had similar laws in place and one does not want to go there again. The infamous Information Scandal in South Africa of some thirty years ago, or Muldergate as it has come to be known, reminds one of what governments can do when it works clandestinely.
 
What South Africans need, is more information on what government structures are doing and how they are doing it with taxpayers’ money, not less information. While information in itself does not equal communication or dialogue, it is an indispensable part thereof, and the need for dialogue based on verifiable information is urgent for meeting vexed challenges facing South African communities. Academics in all fields of specialisation are constantly in need of untainted information to pursue answers and/or offer solutions to where South Africa should be moving in all spheres of life.

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