Time filter

Source Type

Venda S.,Presidency College at Chennai | Peramaiyan G.,Vel Technology University | NizamMohideen M.,The New College Autonomous | Vinitha G.,Vellore Institute of Technology | Srinivasan S.,Presidency College at Chennai
Journal of Optics (India) | Year: 2016

Single crystal of 2-amino 6-methylpyridinium salicylate (2A6MPS) was grown for the first time by the slow evaporation method. Single crystal X-ray diffraction analysis was employed to estimate the cell parameters of the grown crystal. The third order nonlinear optical properties of 2A6MPS was studied by the Z-scan technique using 532 nm diode pumped CW Nd:YAG laser. Nonlinear refractive index, nonlinear absorption coefficient and nonlinear susceptibility of the grown crystal were found to be 10−8 cm2/W, 10−4 cm/W and 10−6 esu, respectively. Thermal stability of 2A6MPS was studied by thermogravimetry (TG) and differential thermal analyses (DTA). The optical transmittance window and the lower cut-off wavelength of 2A6MPS were identified by UV–Vis–NIR studies. From the dielectric measurements, the relative dielectric permittivities ε11 and ε33 values were determined. © 2016 The Optical Society of India

Dhavamurthy M.,Presidency College at Chennai | Peramaiyan G.,Vel Tech Dr.RR & Dr.SR Technical University | Babu K.S.S.,The New College Autonomous | Mohan R.,Presidency College at Chennai
Applied Physics A: Materials Science and Processing | Year: 2015

Organosulfur nonlinear optical single crystals of orthorhombic bis(guanidinium) 5-sulfosalicylate (2CH6N3 +·C7H4O6S2−·H2O) with dimension 14 mm × 4 mm × 5 mm have been grown from methanol and water solvents in 1:1 ratio by the slow evaporation growth technique. The crystal structure and morphology of the crystals have been studied by single-crystal X-ray diffraction. FTIR spectroscopic studies were carried out to identify the functional groups and vibrational modes present in the grown crystals. The UV–Vis spectrum was studied to analyze the linear optical properties of the grown crystals. The thermal gravimetric analysis was conducted on the grown crystals, and the result revealed that the grown crystal is thermally stable up to 65 °C. The dielectric tensor components ε11, ε22 and ε33 of BG5SS crystal were evaluated as a function of frequency at 40 °C. The surface laser damage threshold for the grown crystal was measured using Nd:YAG laser. Further, Vickers micro-hardness study was carried out to analyze the mechanical strength of the grown crystals for various loads. © 2015, Springer-Verlag Berlin Heidelberg.

Jauhar R.M.,Pachaiyappas College | Vivek P.,Pachaiyappas College | Vivek P.,Sri Venkateswara Institute of Technology | Sudhakar K.,Pachaiyappas College | And 3 more authors.
Journal of Thermal Analysis and Calorimetry | Year: 2016

A novel organic nonlinear optical crystal, 2,6 diaminopyridinium tosylate (2,6DPT), was synthesized and grown by the slow evaporation method. Formation of the new crystalline compound was confirmed by single-crystal X-ray diffraction study. The title compound (2,6DPT) crystallizes in the monoclinic crystal system with space group of P21/c. The crystalline perfection of the as-grown crystal was assessed by high-resolution X-ray diffraction study and the quality of it is reasonably good. The thermal stability of 2,6DPT is found to be 180 °C by thermogravimetric and differential thermal (TG–DTA) analyses. The specific heat capacity of 2,6DPT is found to be 3.86 J g−1 K−1. UV–Vis–NIR spectral study showed that the grown crystal is transparent in the entire visible region with the lower cut-off wavelength of 380 nm. The laser-induced surface damage threshold of grown crystal was measured to be 0.2538 GW cm−2 for 1064 nm Nd:YAG laser radiation. Nonlinear refractive index (n2), absorption coefficient (β) and third-order nonlinear susceptibility (χ(3)) were measured by Z-scan technique. © 2015, Akadémiai Kiadó, Budapest, Hungary.

Basith N.M.,Catalysis and Nanomaterials Research Laboratory | Basith N.M.,The New College Autonomous | Vijaya J.J.,Catalysis and Nanomaterials Research Laboratory | Kennedy L.J.,Vellore Institute of Technology
Advanced Materials Research | Year: 2014

Pure and Fe-doped CuO nanostructures with different weight ratios (0.5, 1.0, 1.5, and 2.0 at wt% of Fe) were prepared by a facile and fast microwave combustion method. The structure and morphology of the samples were investigated by X-ray diffraction (XRD), high resolution scanning electron microscopy (HR-SEM), diffuse reflectance spectroscopy (DRS), photoluminescence (PL) spectroscopy and vibrating sample magnetometry (VSM). The XRD patterns refined by the Rietveld method indicated the formation of single-phase monoclinic structure and also confirm that the Fe ions are successfully incorporated into the CuO crystal lattice by occupying Cu ionic sites. Interestingly, the morphology was found to change considerably from nanoflowers to nano-rod and disk-shaped then to nanoparticles with the variation of Fe content. The optical band gap calculated using DRS was found to be 2.8 eV for pure CuO and increases up to 3.4 eV with increasing 'Fe' content. Photoluminescence measurements also confirm these results. The magnetic measurements indicated that the obtained nanostructures are found to show a room temperature ferromagnetism (RTF) with an optimum value of saturation magnetization at 2.0 wt.% of Fe-doped CuO, i.e.1.2960 x 10 -3 emu/g. © (2014) Trans Tech Publications, Switzerland.

Rajasekar M.,The New College Autonomous | Sreedaran S.,University of Madras | Prabu R.,University of Madras | Narayanan V.,University of Madras | And 3 more authors.
Journal of Coordination Chemistry | Year: 2010

Ni(II) and Cu(II) metal complexes of simple unsymmetrical Schiff-base ligands derived from salicylaldehyde/5-methylsalicylaldehyde and ethylenediamine or diaminomaleonitrile (DMN) were synthesized. The ligands and their complexes were characterized by elemental analysis, 1H NMR, FT IR, and mass spectroscopy. The electronic spectra of the complexes show d-d transitions in the region at 450-600 nm. Electrochemical studies of the complexes reveal that all mononuclear complexes show a one-electron quasi-reversible reduction wave in the cathodic region. ESR spectra of the mononuclear copper(II) complexes show four lines, characteristic of square-planar geometry, with nuclear hyperfine spin 3/2. The copper(II) complexes show a normal room temperature magnetic moment value μeff = 1.70-1.74 BM which is close to the spin only value of 1.73 BM. Kinetic studies on the oxidation of pyrocatechol to o-quinone using the copper(II) complexes as catalysts were also carried out. The in vitro antimicrobial activity of the investigated compounds was tested against human pathogenic bacterias such as Staphylococcus aureus, Bacillus subtilis, Klebsiella pneumonia, Pseudomonas aeruginosa and Escherichia coli. The antifungal activity was tested against Candida albicans. Generally, the metal complexes have higher antimicrobial activity than the free ligands. © 2010 Taylor & Francis.

Discover hidden collaborations