1. Department of Chemistry, Faculty of Science; Universiti Putra Malaysia; 43400 UPM Serdang Selangor Malaysia
2. Functional Device Laboratory, Institute of Advanced Technology; Universiti Putra Malaysia; 43400 UPM Serdang Selangor Malaysia
3. Low Dimension Materials Research Centre, Department of Physics, Faculty of Science; University of Malaya; Kuala Lumpur 50603 Malaysia