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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

UV vestig hom afgelope eeu as leier op verskeie terreine
2004-05-11

Michelle O'Connor - Volksblad - 11 Mei 2004

Ondank terugslae nou 'n 'gesonde volwassene'

HOEWEL die Universiteit van die Vrystaat (UV) vanjaar sy eeufees vier en met 23 000 studente die grootste universiteit in die sentrale deel van die land is, was dié instelling se geboorte glad nie maklik nie. MICHELÉ O'CONNOR het met prof. Frederick Fourie, rektor, oor die nederige begin van dié instelling gesels.

DIE behoefte aan 'n eie universiteit in die Vrystaat het reeds in 1855, kort ná die stigting van Grey-kollege, kop uitgesteek.

Grey se manne het hulleself teen 1890 begin voorberei om die intermediêre B.A.-eksamens af te lê. Dié eksamen het hulle toegang gegee tot die tweede jaar van 'n B.A.-graad aan die destydse University of the Cape Good Hope, nou die Universiteit van Kaapstad.

"Presidente F.W. Reitz en M.T. Steyn het destyds albei die stigting van 'n universiteit hier bepleit. Die grootste rede was sodat die seuns van die Vrystaat nie weggestuur word nie.

"Dié twee se droom is op 28 Januarie 1904 bewaarheid toe ses studente hulle onder dr. Johannes Bril, as hoof/rektor van Grey-kollege, vir die graad B.A. ingeskryf het. Dié graad is aanvanklik deur die Kaapse universiteit toegeken.

"Net die klassieke tale soos Latyns en Grieks, die moderne tale, Nederlands, Duits en Engels, filosofie, geskiedenis, wiskunde, fisika, chemie, plant- en dierkunde is aanvanklik aangebied.

"Die UV se geboue het gegroei van 'n klein tweevertrek-geboutjie wat nou naby Huis Abraham Fischer staan, en verblyf in die Grey-kollege se seunskoshuis," sê Fourie.

Volgens hom is die universiteit se eerste raad en senaat tussen 1904 en 1920 saamgestel. Die eerste dosente is aangestel en die eerste geboue opgerig. "Dié tyd was egter baie moeilik.

"Die instelling het teen 1920 net 100 studente gehad en was geldelik in die knyp. Daar was geen vaste rektor nie en geen vooruitgang nie. Vrystaatse kinders is steeds na ander universiteite gestuur.

"Ds. J.D. Kestell, rektor van 1920 tot 1927, het egter dié instelling finaal gevestig.

"Hy het self studente van oor die hele Vrystaat gewerf en geld by onder meer kerke en banke ingesamel. Kestell het selfs Engelse ouers oortuig om hul kinders na die Greyuniversiteitskollege (GUK) te stuur en teen 1927 het dié instelling met 400 studente gespog.

"In die tydperk tussen 1927 en 1950 het die GUK weer verskeie terugslae beleef.

"In dié tyd was dit onder meer die Groot Depressie en die Tweede Wêreldoorlog. Die armblanke-vraagstuk het regstreeks op studente en dosente ingewerk en die politieke onderstrominge van dié tyd het die instelling ontwrig.

"Die GUK het egter oorleef en die Universiteitskollege van die Oranje-Vrystaat (UKOVS) is in 1935 gebore," sê Fourie.

Hy sê in dié tyd is verskeie fakulteite gevestig en teen 1950 het die UKOVS met 1 000 studente gespog.

Teen 1950 het dit 'n onafhanklike universiteit geword en die naam is verander na die Universiteit van die OranjeVrystaat (UOVS).

Dié tydperk is gekenmerk deur Afrikaner- en blanke selfvertroue en heerskappy. Studentegetalle het tot 7 000 in 1975 gegroei en heelwat vooruitgang het in dié tyd plaasgevind.

"Tussen 1976 en 1989 sukkel dieuniversiteit weer met onder meer ekonomiese krisisse, die land se politieke onstabiliteit en word die UOVS geï soleer.

"Een ligpunt in dié tyd is die toelating van die eerste swart studente, die nuwe Sasol-biblioteek en die fakulteit teologie wat die lig sien.

"Tussen 1990 en vanjaar het die UOVS verskeie op- en afdraandes beleef. Die universiteit doen nie net die eerste stappe van transformasie nie, maar begin ook aan 'n beleid van multikulturaliteit werk.

"Die UOVS se naam verander in 1996 na die Universiteit van die Vrystaat/University of the Free State en in 2001 word die Sotho-vertaling bygevoeg.

"Geldelike druk en probleme neem drasties toe en personeel word gerasionaliseer.

"Teen 2000 begin die UV met 'n draaistrategie en studentegetalle neem tot meer as 23 000 toe," sê Fourie.

Hy sê die UV het die afgelope eeu nie net verskeie terugslae oorleef nie, maar homself ook op verskeie gebiede as 'n leier gevestig.

Die universiteit behaal sy eie geldelike mikpunte, neem 'n nuwe taalbeleid van veeltaligheid aan en herbelê in personeel.

Die instelling inkorporeer die kampusse van die Vista- en Qwaqwa-universiteit en groei internasionaal.

Die UV vestig ook fondamente van 'n institusionele kultuur van verdraagsaamheid, geregtigheid en diversiteit.

"Die baba het in die afgelope eeu 'n gesonde volwassene geword."

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