1. Natural Sciences Research Institute, University of the Philippines Diliman, Quezon City 1101, Philippines
2. Advanced Device and Materials Testing Laboratory, Department of Science and Technology Compound, Gen. Santos Avenue, Bicutan, Taguig City 1631, Philippines
3. National Institute of Physics, University of the Philippines Diliman, Quezon City 1101, Philippines
4. Institute of Chemistry, University of the Philippines Diliman, Quezon City 1101, Philippines