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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

Unconventional oil and gas extraction – study for Water Research Commission reveals possible impacts
2014-11-05

 

Photo: Legalplanet.org
The Centre for Environmental Management (CEM) at the University of the Free State (UFS) recently completed a three-year project for the Water Research Commission. The purpose was to develop an interactive vulnerability map and monitoring framework for unconventional oil and gas extraction (final report still to be published).

Due to the complexity of this field, a number of participants across different disciplines and universities were involved in this trans-disciplinary study. Contributors included the Departments of Sociology, Physics and Mathematical Statistics from the UFS, the University of Pretoria Natural Hazard Centre, Africa, as well as the Institute of Marine and Environmental Law from the University of Cape Town.

Unconventional oil and gas extraction, its related impacts and the management of this activity to ensure environmental protection, is a controversial issue in many countries worldwide. Since the extraction of oil and gas using unconventional techniques is an unprecedented activity in South Africa, the project focused on understanding this extraction process as well as hydraulic fracturing and identifying possible environmental and socio-economic impacts associated with this activity in the South African context. An understanding of the possible impacts could aid government during the development of policy aimed at protecting the environment.

The researchers subsequently identified indicators to develop an interactive vulnerability map for unconventional oil and gas in South Africa. The vulnerability map focuses on specific mapping themes, which include surface water, groundwater, vegetation, seismicity and socio-economics. In addition, the map provides information on the vulnerability of the specified mapping themes to unconventional gas extraction on a regional scale. This map is intended as a reconnaissance tool to inform decision-makers on areas where additional detail field work and assessments may be required. It can also be used during Environmental Impact Assessments and determining licensing conditions.

Lastly, a monitoring framework was developed, which describes monitoring requirements for specific entities – surface water, groundwater, vegetation, seismicity and socio-economics – for the different phases of unconventional oil and gas extraction. Such monitoring is an important part of environmental protection. It is especially important for South Africa to perform baseline monitoring before exploration starts to ensure that we will have reference conditions to identify what impact oil and gas extraction activities has on the biophysical and socio-economic environments.


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