1. Department of Chemistry, Dibrugarh University, Dibrugarh, 786004, India
2. Department of Physics, The Assam Kaziranga University, Koraikhowa, Jorhat, Assam 785006, India
3. Coal & Energy Division, CSIR − North East Institute of Science and Technology (NEIST), Jorhat, Assam 785006, India
4. Department of Chemistry, MDKG College, Dibrugarh, Assam 786001, India
5. Department of Chemical Sciences, Tezpur University, Tezpur, Assam 784028, India
6. Department of Physics, JB College, Jorhat, Assam 785001, India