1.       2011: HAA Seed Ahmed, WD Roos, OM Ntwaeaborwa, HC Swart and RE Kroon. Effect of annealing on the Ce3+/Ce4+ ratio measured by XPS in luminescent SiO2:Ce. Proceedings of SAIP2011, the 56th Annual Conference of the South African Institute of Physics, edited by I. Basson and A.E. Botha (University of South Africa, Pretoria). ISBN: 978-1-86888-688-3. pp. 280-284.

2.       2011: RE Kroon, HAA Seed Ahmed and MA Gusowski. The impurity levels of lanthanide ions in silica. Proceedings of SAIP2011, the 56th Annual Conference of the South African Institute of Physics, edited by I. Basson and A.E. Botha (University of South Africa, Pretoria). ISBN: 978-1-86888-688-3. pp. 162-167.

3.       2012: RE Kroon, HAA Seed Ahmed, OM Ntwaeaborwa, LF Koao, IM Nagpure, MA Gusowski, JR Botha and HC Swart. Luminescence from Ce in sol–gel SiO2. Physica B: Condensed Matter 407 1595–1598.

4.       2012: HAA Seed Ahmed, OM Ntwaeaborwa, MA Gusowski, JR Botha and RE Kroon. 5D3→7FJ emission of Tb doped sol–gel silica. Physica B: Condensed Matter 407 1653–1655.

5.       2012 HAA Seed Ahmed, OM Ntwaeaborwa and RE Kroon. High efficiency energy transfer in Ce,Tb co-doped silica prepared by sol-gel method. Journal of Luminescence. 135 15–19

6.      HAA Seed Ahmed, W-S Chae, OM Ntwaeaborwa and RE Kroon. Interaction mechanism for energy transfer from Ce to Tb ions in silica. Proceedings of SAIP2012, the 57th Annual Conference of the South African Institute of Physics (University of Pretoria, Pretoria).

7.       2013 HAA Seed Ahmed, OM Ntwaeaborwa and RE Kroon. The energy transfer mechanism in Ce,Tb co-doped LaF3 nanoparticles. Current Applied Physics 13 1264–1268

 8.       2014 R.E. Kroon, H.C. Swart, O.M. Ntwaeaborwa and H.A.A. Seed Ahmed. Ce decay curves in Ce,Tb co-doped LaF3 and the energy transfer mechanism. Physica B: Condensed Matter 439 83–87.