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27 July 2021 | Story Leonie Bolleurs | Photo UFS Photo Archive
Prof Hendrik Swart played a key role in the Department of Physics acquiring the PHI Quantes XPS system, the first in Africa and one of only 20 in the world.

The state-of-the-art equipment in the Department of Physics at the University of the Free State (UFS) differentiates this department from its competitors. Availability of the equipment makes it possible for researchers as well as students to deliver work that receives national and international recognition. 

Recently, the department acquired a PHI Quantes XPS system, the first in Africa and one of only 20 in the world. 

Creating better phosphor 

“The Quantes XPS system uses X-rays to determine the chemical composition of molecules on the surface of a sample. The system is unique in the sense that it also has an extra X-ray source that can determine the chemical state below the surface, which was not possible in the past.  This will help us to dictate the position of defects in our phosphor materials that will consequently enable us to create better phosphor for solid state lighting as well as solar cell applications,” explains Prof Hendrik Swart, Senior Professor in the Department of Physics, who also holds the SARChI Chair in Solid State Luminescent and Advanced Materials.

After he had the opportunity to observe the system in the factory in Chigasaki, Kanagawa, Japan, where he attended a conference, Prof Swart was very impressed by its performance. He discussed it with Prof Koos Terblans, Head of the department, and other colleagues, and started making plans to buy the system. 

When the department first bought the X-ray photoelectron spectroscopy (XPS) system in 2007/2008, it became the national facility on XPS measurements. Not only is this an upgrade of the XPS system bought 14 years ago, but the new system will enable the department to do more measurements. “The number of samples that we have to handle has just become too much for one system. The new system’s increased capacity for making measurements addresses this challenge and it also gives UFS scientists and postgraduate students more time to spend on fundamental measurements to develop research of a higher level,” says Prof Swart.

(The Quantes XPS system. Photo:Supplied)

Explaining about the measurements, Prof Swart says: “This advanced X-ray photoelectron spectroscopy (XPS) instrument has the capability to analyse the very small area that the user is interested in and a large area of the uniform sample surface. The two different types of X-ray sources – the hard X-ray source and the more conventional soft X-ray source – can be switched automatically, allowing users to analyse the same area and/or points of a sample. The PHI Quantes XPS system ensures the availability of superior features such as automatic analysis, automatic sample transfer, turnkey charge neutralisation, and advanced data processing.”

“This XPS instrument is designed to pioneer new methods and applications transcending conventional ideas of what is possible.”

Optimising efficiency of materials

Prof Swart says the Department of Physics, especially the Research Chair in Advanced and Luminescent Materials, is developing new high-technology materials on a daily basis. “It is very important to know the chemical composition and defect distribution of the materials in order to add value to the fabrication of these materials,” he adds.

“The distribution of these defects is vital for the efficiency of the phosphor materials. If we know where these defects are located, we can determine the mechanisms of the light output coming from these phosphors,” describes Prof Swart.

Research conducted as part of the Research Chair in Solid State Luminescent and Advanced Materials will benefit significantly from this new system.

(Prof Koos Terblans, Head of the Department of Physics next to the Quantes XPS system. Photo:Supplied) 

“We are currently concentrating on phosphors as sensors (temperature), light-emitting diodes (LEDs), and solar cells, where we optimise the efficiency and durability of these materials. Any new knowledge, which I believe the PHI Quantes XPS system will provide us, will help us to reach our goal much quicker,” he says. 

Apart from the positive impact on research, the PHI Quantes XPS system will also be a benefit to society in the long term. Improved LEDs can be used to save electricity, and better solar cells can help to generate electricity, to mention but two examples. 

News Archive

Chemistry research group receives international recognition
2016-10-28

Description: Chemistry research group  Tags: Chemistry research group

Dr Carla Pretorius mounts microcrystals with
Dumisani Kama while Pennie Mokolokolo
observe the technique.
Photo: Supplied


Crystals and crystallography form an integrated part of our daily lives, from bones and teeth, to medicines and viruses, new catalysts, jewellery, colour pigments, chocolates, analysing rocks on the moon and Mars, electronics, batteries, metal blades in airplane turbines, panels for solar energy and many more.

In spite of this, not many people know much about X-ray crystallography, although it is probably one of the greatest innovations of the 20th century, spanning the sciences. That is why this discipline is actively researched by a number of tertiary institutions around the globe as well as the Inorganic Chemistry Group of the Department of Chemistry at the University of the Free State (UFS).

Research by the Inorganic Chemistry Group includes:
•    clever design of model medicines to better detect cancer and study heart, bone and brain defects;
•    production of new compounds for making new and better automobile fuels and decrease carbon dioxide in the atmosphere;
•    generation and purification of new South African mineral resources for metals widely used in turbines which use wind energy.

A group of UFS students have received acknowledgement for their research at six international venues in the past few months.

Posters in Cameroon
Twelve postgraduate students, together with Prof André Roodt, Head of the Inorganic Chemistry division at the UFS, delivered three oral presentations, nine posters, one plenary and one keynote lecture abroad.

Four UFS students - Nina Morogoa, Pheello Nkoe, Alebel Bilay, and Mohammed Elmakki - who delivered posters at the First Pan African Conference on Crystallography in Dschang, Cameroon, received prizes for their presentations.

School and conference in Croatia

Students Orbett Alexander and Dumisani Kama were selected to attend the intense and demanding Third European Crystallographic School in Bôl, Croatia. Both Kama, Alexander and Prof Roodt gave oral presentations at the 24th Croatian-Slovenian Crystallographic Meeting at Brac Island, Croatia.

Kama, together with Dr Ferdi Groenewald, Dr Carla Pretorius and Pennie Mokolokolo, also attended the European Synchrotron Radiation Facility (ESRF) in Grenoble, France. The ESRF is a centre of excellence for fundamental and innovation-driven research. The storage ring at this laser facility can generate X-rays 100 billion times brighter than typical medical and laboratory X-ray sources.

Research in Switzerland

Kama and Mokolokolo also spent one month on research visits at the University of Zurich in Switzerland. Both Kama and Alexander were invited to present their research orally to the Institute of Inorganic Chemistry in Zurich, headed by Prof Roger Alberto.

In Basel, Switzerland, Dr Ferdi Groenewald, Dr Renier Koen, and Dr Truidie Venter all presented their research at the 30th European Crystallographic Meeting.

Prof Roodt said: “It is incredibly important that our postgraduate students get the chance to interact, discuss, and be taught by the best in the world and realise that hard work on basic and applied chemistry processes leads to broader recognition. The delegates to these international venues came from more than 60 countries and took note of our students work. With these young researchers, our future at the UFS and at Inorganic Chemistry is in good hands”.

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