1. DST/CSIR National Centre for Nano-Structured Materials
2. Council for Scientific and Industrial Research
3. Pretoria 0001
4. South Africa
5. Institute of Electronic Structure and Laser
6. Foundation for Research and Technology
7. Heraklion 71110
8. Greece
9. Department of Physics
10. University of the Free State
11. Bloemfontein ZA9300