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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

UFS alumnus receives PhD in Statistics from the University of Oxford
2016-06-03

Description: DW Bester  Tags: DW Bester

In May of this year, DW Bester obtained
a DPhil in Statistics at the University of
Oxford.
Photo: Supplied

On 14 May this year, Dr DW Bester received a DPhil in Statistics from the University of Oxford. The entire ceremony, which was held in the Sheldonian Theatre in Oxford, was conducted in Latin, as has been the case for the past 800 years.

Dr Bester completed his undergraduate studies and his honours degree at the University of the Free State (UFS). “At first, I was only planning to study for a master’s degree, but was privileged to get an opportunity to do a PhD as well. I didn’t think twice!” he says.

Studies at the University of Oxford


Universities in England do not require a master’s degree for PhD studies. With the help of Prof Max Finkelstein from the UFS Department of Mathematical Statistics and Actuarial Science, Dr Bester registered for the DPhil programme in Statistics directly after his honours studies.

“The title of my thesis was: Joint survival models: A Bayesian investigation of longitudinal volatility. It dealt with a problem in the medical field to determine the cause of stroke risk: is it the absolute level of blood pressure, or the volatility thereof? The analysis of this question led to interesting models which needed advanced application techniques. I had to study these techniques and write programmes for their application.

Although Dr Bester is working currently as the technical head of a company that calculates insurance for power stations, satellites, rockets, and cyber risks, he would like to continue working with his Oxford supervisor in future to make the techniques they have developed more accessible for researchers outside of the field of statistics.
 
“Studying at Oxford requires hard work, perseverance, and a lot of luck. Luck plays a big role, since there are no guarantees that hard work will ensure you a spot in one of the top universities.

Regarding his studies at Oxford, Dr Bester thinks back on his exposure to the GNU/Linux operating system, and free software. “I have seen how valuable this is for analyses in practice. I also had the privilege of meeting the father of free software, Richard Stallman,” Dr Bester says.

2011 Rhodes Scholar

He was elected as Rhodes Scholar in 2011. According to Dr Bester, who has been interested in Mathematics since high school, the Rhodes scholarship was something of a fluke. He applied for the Rhodes scholarship on the recommendation of Prof Robert Schall of the Department of Mathematical Statistics and Actuarial Science.

Role of the UFS in his successes


In addition to the continued support from the team of passionate professors and lecturers at the UFS, the actuarial degree at the UFS is fraught with statistics. Emphasis is also placed on Bayesian statistics. This was crucial to his studies at Oxford. According to Dr Bester, this topic is emphasised strongly in the international statistics community.

Dr Bester regards the work done by two of his lecturers, Michael von Maltitz and Sean van der Merwe, among his highlights at the UFS. Since our first year, they have created an atmosphere of camaraderie among the students. “I think this contributed to the success of everybody. They also make an effort to present topics outside of the syllabus regularly,” says Bester.

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