Browsing by Author "Selvakumar, S."

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Characterization of a newly synthesized organic nonlinear optical crystal: benzoyl valine
(2010-05-01)
Kumar, T. K.
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Selvaraj, R. S.
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Janarthanan, S.
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Rajan, Y. C.
;
Selvakumar, S.
Herein the synthesis and the crystal growth of benzoyl valine (BV), an organic nonlinear optical (NLO) material for frequency conversion was grown by slow evaporation solution growth technique at room temperature has been reported. The compound was prepared by Stockman method of benzoylation. The solubility curve shows linear nature up to a temperature of 313 K. XRD study reveals that the crystal belongs to monoclinic system with P2(1) non-centrosymmetric space group. The fundamental vibrational frequency of various functional groups (400-4000 cm(-1)) in the crystal was determined from FTIR analysis. (1)H and (13)C NMR spectral studies reveal the presence of proton and carbon network in the grown crystalline sample. The optical behaviour of the crystal was ascertained by optical UV absorption spectral studies. The UV cut off region (gimel(max)) lies around 200 nm and the crystal is absolutely transparent from 220800 nm suggesting its application as NLO material. The thermal stability of the crystal was determined by thermogravimetric and differential thermal analyses. Laser damage threshold of BV was found to be 0.34 GW/cm(2) and hence BV can be used in frequency doubler system. Photoconductivity study of BV revealed negative photoconductiviting nature of the sample. The microhardness studies confirm that BV has a moderate Vickers hardness number (VHN) value in comparison to the other organic NLO crystals.
Growth and Characterization of Organic NLO Crystal: beta-Naphthol
(2011-03-01)
Janarthanan, S.
;
Samuel, R. Sugaraj
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Selvakumar, S.
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Rajan, Y. C.
;
Jayaraman, D.
Single crystals of beta-Naphthol (beta N), an organic nonlinear optical (NLO) material was successfully grown by temperature lowering method using chloroform as solvent. The initial compound was purified by repeated recrystallization process. As-grown crystals were characterized by single crystal X-ray diffraction (XRD) studies to ascertain that beta N crystal crystallized in the monoclinic system with a noncemtrosymmetric space group. Vibrational frequencies of various functional groups in the crystals were derived from Fourier transform infrared (FTIR) spectroscopy and proton nuclear magnetic resonance (NMR) spectrum. Optical characterization was done using UV-Visible near-infrared (NIR) spectroscopy. The thermal behaviour of the material was studied by thermo gravimetric and differential thermal plots. Scanning electron microscopy (SEM) study was carried out on the surface of the grown crystals to investigate the nature of defects in the crystal surface and the NLO property of the crystal was tested by Nd:YAG laser as a source.
Synthesis and characterization of semicarbazone of p-hydroxy-3-methoxy acetophenone (SPH3MA) single crystal
(2011-01-15)
Janarthanan, S.
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Rajan, Y. C.
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Umarani, P. R.
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Selvakumar, S.
;
Pandi, S.
Single crystals of semicarbazone of p-hydroxy-3-methoxy acetophenone (SPH3MA) were grown by a slow evaporation solution growth technique at room temperature. This is the first report in the literature on the crystallization of SPH3MA. The cell parameters of the grown crystals were estimated by single crystal X-ray diffraction analysis. The various planes of reflection were identified from the XRD powder pattern. The presence of functional groups was identified from FTIR and (1)H NMR. The results were found to be in accordance with the structure of the crystal. The formation of charge transfer complex was confirmed by UV-vis-NIR spectroscopy. The thermal stability of the grown crystal was studied by thermal analysis. (C) 2010 Elsevier B.V. All rights reserved.