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Rahulan K.M.,SRM University | Balamurugan S.,Universiti Sains Malaysia | Meena K.S.,Queen Marys College | Yeap G.-Y.,Universiti Sains Malaysia | Kanakam C.C.,SRM University
Optics and Laser Technology | Year: 2014

3-(4-(dimethylamino)phenyl)-1-(4-(4-(hydroxymethyl)-1H-1,2,3-triazol-1-yl) phenyl)prop-2-en-1-one was synthesized and its third order nonlinear optical properties have been investigated using a z-scan technique with nanosecond laser pulses at 532 nm. The nonlinear absorption behavior of the compound in chloroform presents a distinct difference at different laser intensity. Interestingly, the compound showed a switchover from saturable absorption (SA) to reverse saturable absorption (RSA) with the increase of excitation intensity. Our studies suggest that compound could be used as a potential candidate for optical device applications such as optical limiters. © 2013 Elsevier Ltd. Source

Surekha R.,Prathyusha Institute of Technology and Management | Sagayaraj P.,Loyola College | Ambujam K.,Queen Marys College
CrystEngComm | Year: 2014

l-Phenylalanine l-phenylalaninium bromide (LPLPB), an amino acid non-centrosymmetric crystal having a large second harmonic generation (SHG) efficiency, being 4.5 times that of KH2PO4 (KDP), has been successfully grown using a slow evaporation method employing a temperature gradient technique. The structure of the grown crystal was solved and refined by single-crystal X-ray diffraction, and this demonstrates that it belongs to a monoclinic system with the space group P21. The confirmation of its functional groups was recorded using Fourier transform infrared spectroscopy. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were used to study its thermal properties. The optical behaviour was examined and its optical constants were determined by UV-vis analysis. Dielectric spectroscopy reveals the dielectric nature of the grown crystal. The mechanical strength of the grown LPLPB was estimated by microhardness studies, and the Young's modulus of the grown LPLPB was calculated to be 3.310 × 10 10 N m-2. This journal is © the Partner Organisations 2014. Source

Kalaiselvi D.,Queen Marys College | Jayavel R.,Anna University
Applied Physics A: Materials Science and Processing | Year: 2012

A semi-organic nonlinear optical L-proline dimercuricchloride (LPDMC) material has been synthesized. LPDMC single crystals were grown from aqueous solution by a slow cooling method. Good quality single crystals of size 19×6×3 mm 3 have been grown over a period of 3 weeks. The grown crystals have been subjected to single crystal X-ray diffraction analysis to determine the cell parameters. The title compound crystallizes in the triclinic system with a noncentrosymmetric space group P1 and with unit-cell parameters a=7.2742(4) Å, b=9.4472(5) Å, c=10.4767(6) Å, α=108.621(3)°, β=107.260(2)°, γ=97.353(2)° and volume=631.51(6) Å 3. Optical and dielectric properties of the crystals have been studied. The thermal stability of the crystals was determined by thermogravimetric analysis/differential thermal analysis. The second harmonic generation efficiency of the crystals was obtained by the classical powder technique using a Nd:YAG laser and it is found to be 2.5 times that of potassium dihydrogen phosphate. © 2012 Springer-Verlag. Source

John R.,University of Madras | Rajakumari R.,Queen Marys College
Nano-Micro Letters | Year: 2012

Zinc oxide (ZnO) doped with erbium at different concentrations was synthesized by solid-state reaction method and characterized by X-ray diffraction (XRD), scanning electron microscopic (SEM), UV- absorption spectroscopy, photoluminescence (PL) study and vibrating sample magnetometer. The XRD studies exhibit the presence of wurtzite crystal structure similar to the parent compound ZnO in 1% Er 3+ doped ZnO, suggesting that doped 3+ ions sit at the regular Zn 2+ sites. However, same studies spread over the samples with 3+ content>1% reveals the occurrence of secondary phase. SEM images of 1% 3+ doped ZnO show the polycrystalline nature of the synthesized sample. UV-visible absorption spectrum of 3+ doped ZnO nanocrystals shows a strong absorption peak at 388 nm due to ZnO band to band transition. The PL study exhibits emission in the visible region, due to excitonic as well as defect related transitions. The magnetization- field curve of 3+ doped ZnO nanocrystals showed ferromagnetic property at room-temperature. Source

Surekha R.,Prathyusha Institute of Technology and Management | Sagayaraj P.,Loyola College | Ambujam K.,Queen Marys College
Optical Materials | Year: 2014

Optical quality bis glycine hydrobromide (BGHB) single crystal was grown by slow evaporation technique. The third order nonlinear refractive index and nonlinear absorption coefficient of the grown crystal were measured by Z-scan studies. The third order nonlinear susceptibility was found to be 9.612 × 10-4 esu which is fairly higher than the other glycine compounds. The Photoluminescence spectra reveal the emission bands for BGHB crystals. The band gap energy was calculated to be 3.1 eV. The Photoconductivity studies were employed to determine the dependence of photocurrent on the applied electric field. Negative photoconductivity was exhibited by the sample. The d.c. conductivity of the grown crystal was measured by the complex impedance analysis wherein the obtained plot in the form of semicircle finds application in Debye relaxation for materials having large dc conductivity. © 2014 Elsevier B.V. All rights reserved. Source

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