Faculty Publications
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Item Optical nonlinearity, limiting and switching characteristics of novel ruthenium metal-organic complex(Elsevier B.V., 2017) Manjunatha, K.B.; Rajarao, R.; Umesh, G.; Badekai Ramachandra, B.R.; Poornesh, P.We report the nonlinear optical properties of Ruthenium metal complex a promising organic material for use in scientific and technological applications. The thin films of newly synthesized ruthenium metal–organic complex were fabricated using spin coating technique. Z-scan and degenerate four wave mixing (DFWM) techniques used to extract the third-order nonlinear optical (NLO) parameters. The data reveals the investigated material exhibited relatively large NLO properties. The pump–probe experiments shows that the switch-on and off times of the material were in the order of ?s at different pump intensities and the energy dependent transmission studies reveal good limiting property of the material in nanosecond regime. © 2017 Elsevier B.V.Item Enhanced photostability and optical nonlinearity of nickel and cobalt organometallic complexes(Elsevier B.V., 2019) Manjunatha, K.B.; Rajarao, R.; Poornesh, P.; Rudresha, B.J.; Umesh, G.; Badekai Ramachandra, B.R.Nonlinear optical and limiting properties of nickel, cobalt metal-organic complexes and ligand (L) {L = N,N?-o-phenylenebis (4-hyrdoxy-salicylideneimine)} were studied using Z-scan technique using Q-switched Nd: YAG laser with nanosecond pulses at 532 nm. The results reveal that metal complexes exhibit large negative nonlinear refractive index (n2) of the order of 10?11 esu. The metal complexes displays large nonlinearity than the ligand due to effective charge delocalization between metal ion and ligand. The magnitude of ground state absorption cross section is small compared to the effective excited-state absorption cross section implying the observed nonlinearity is due to reverse saturable absorption. Further, metal-organic complexes exhibit enhanced optical limiting behaviour at nanosecond laser pulses. © 2019 Elsevier B.V.Item Simultaneous adsorption of methylene blue and heavy metals from water using Zr-MOF having free carboxylic group(Elsevier Ltd, 2021) Nimbalkar, M.N.; Badekai Ramachandra, B.R.Industrial effluents contain multiple pollutants, which affect the quality of water remediation operations. Hence, it is important to understand the outcome of the multicomponent adsorption system to develop efficient decontamination process. In this work, acid assisted hydrothermal method (reflux temperature at atmospheric pressure) was employed to synthesize zirconium based metal-organic framework (MOF) and utilized for the adsorptive removal of methylene blue (MB) dye and heavy metals (lead and cadmium) from aqueous solution. The adsorbent was characterized by powder X-ray diffraction (PXRD), which confirms the face centered cubic (FCC) crystal structure similar to previously reported UiO-66. Brunauer–Emmett–Teller (BET) and surface area analysis shows that, the MOF has surface area of 505 m2.g?1 and micropores ranging from 0.4 to 0.7 nm. Fourier transform infrared spectroscopy (FTIR) analysis corroborate the presence of free carboxylic groups at 1710 cm?1, apart from this FTIR confirms the presence of regular bands of metal-carboxylic bonds. X-ray photoelectron spectroscopy (XPS) analysis of the adsorbent was conducted to understand the nature of adsorbate-adsorbent interaction and to confirm the loading of metal ions on adsorbent after adsorption. The morphological nature of the MOF was analyzed by scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDX). Effects of various parameters such as pH, adsorbent dosage, adsorption time and effect of initial concentration of adsorbates on adsorption were evaluated. Kinetics and isotherm studies were conducted to understand the nature and extent of adsorption. Langmuir monolayer adsorption capacity of the adsorbent for cadmium, lead and methylene blue were found to be 37 mg.g?1, 100 mg.g?1 and 169 mg.g?1 respectively. © 2021 Elsevier Ltd