1. Industrial Chemistry, Faculty of Science and Natural Resources, Universiti Malaysia Sabah, 88400 Kota Kinabalu, Sabah, Malaysia
2. Department of Physics, Bernal Institute, University of Limerick, Limerick V94 T9PX, Ireland
3. Department of Applied Science, Technological University of the Shannon: Midlands Midwest, Moylish, Limerick V94 EC5T, Ireland