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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

Space-based information plays vital role in disaster-risk reduction
2017-02-28

Africa is one of the continents most affected by disasters triggered by natural hazards. The result of climate change is a reality that affects every human being, whether it is extreme heat waves, cyclones, or the devastation of drought and floods. Climate change can provoke injuries or fatalities and affects the livelihoods of people in both rural communities and urban areas. It triggers damage and losses in various sectors of development, such as housing, road infrastructure, agriculture, health, education, telecommunications, energy, and affects routine economic processes leading to economic losses.

According to Dr Dumitru Dorin Prunariu, President of the Association of Space Explorers Europe, space programmes have become an important force defining challenges of the 21st century. “Space observation is essential for climate-change monitoring,” he said.

Dr Prunariu was the keynote speaker at a two-day symposium on climate resilience and water that was hosted by the Disaster Management Training and Education Centre for Africa (DiMTEC), at the University of the Free State (UFS). He participated in the Soviet Union’s Intercosmos programme and completed an eight day-mission on board Soyuz 40 and the Salyut 6 space laboratory, where he and fellow cosmonaut Leonid Popov completed scientific experiments in the fields of astrophysics, space radiation, space technology, space medicine, and biology. He is the 103rd human being to have travelled to outer space.

The focus of Dr Prunariu’s lecture was: Space activities in support of climate change mitigation and climate resilience.

Description: Dr Dumitriu Dorin Prunariu Tags: Dr Dumitriu Dorin Prunariu

Dr Dumitru Dorin Prunariu, the 103rd human
being in outer space and President of
the Association of Space Explorers Europe.
Photo: Charl Devenish

Space-based information, an extra eye that can detect a way out during disasters
“For governments to support communities affected by any disaster, precise and up-to-date information on its impacts is essential as a way to respond in a timely and effective way,” said Dr Prunariu.

Space-based information (derived using Earth observation, global navigation satellite systems, and satellite communications) can play a vital role in supporting disaster-risk reduction, response, and recovery efforts, by providing accurate and timely information to decision-makers.

“With space-based information, disaster management teams will be able to take note of recently established roads that may not appear in typical maps produced by National Geographic Institutes, but which could be used as emergency evacuation routes or as roads to deliver humanitarian assistance to those who require it in remote areas."

Space-based tools help decision-makers to improve planning
“Space-based tools and spatial data infrastructure is also crucial for policy planners and decision-makers in increasing the resilience of human settlements. Using geographic data and information collected before the occurrence of major disasters in combination with post-disaster data could yield important ideas for improved urban planning, especially in disaster-prone areas and highly-populated regions.

“In the recovery process, information on impact is used by governments to provide assistance to those affected, to plan the reconstruction process, and to restore the livelihoods of those affected,” said Dr Prunariu.

“Space observation is
essential for climate-
change monitoring.”

The symposium was attended by representatives from Liberia, Nigeria, Kenya, Ghana, Namibia, and Zimbabwe, with various international scientists from Europe imparting their expert knowledge on water and global resilience. The presence of these international experts strengthened global networks.

It isn't important in which sea or lake you observe a slick of pollution, or in the forests of which country a fire breaks out, or on which continent a hurricane arises, you are standing guard over the whole of our Earth. - Yuri Artyukhin: Soviet Russian cosmonaut and engineer who made a single flight into space.

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