1. Materials for Energy Research group, Material Physics Research Institute, School of Physics, University of the Witwatersrand, Private Bag 3, Wits, 2050 Johannesburg, South Africa
2. School of Chemistry, University of the Witwatersrand, Private Bag 3, Wits 2050, South Africa
3. Historical Museum of Physics and Study & Research Centre “Enrico Fermi”, 00184 Roma, Italy
4. ENGAGE, University of Pretoria, Private Bag X20, Pretoria 0028, South Africa
5. University of West Attica, Perou Ralli & Thevon 250, Egaleo, Greece