Author
Hema Tresa Varghese
Other affiliations: Mar Ivanios College
Bio: Hema Tresa Varghese is an academic researcher from Fatima Mata National College. The author has contributed to research in topics: Hyperpolarizability & Raman spectroscopy. The author has an hindex of 28, co-authored 128 publications receiving 2405 citations. Previous affiliations of Hema Tresa Varghese include Mar Ivanios College.
Papers
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TL;DR: FT-IR and FT-Raman spectra of Vitamin c have been recorded and analysed and the molecule is thought to adsorb with the lactone ring in a tilted side on orientation with respect to the silver surface.
171 citations
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TL;DR: Surface enhanced Raman scattering (SERS) spectrum was recorded is silver colloid because sodium salicylate is thought to adsorb in a somewhat 'tilted side on orientation' with respect to the silver surface.
114 citations
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TL;DR: The optimized molecular structure, vibrational frequencies, corresponding vibrational assignments of 5-nitro-2-(4-Nitrobenzyl) benzoxazole have been investigated experimentally and theoretically using Gaussian09 software package and the calculated geometrical parameters are in agreement with that of similar derivatives.
70 citations
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TL;DR: FT-IR and FT-Raman spectra of 4-chloro-2-(3,4-dichlorophenylcarbamoyl)phenyl acetate were recorded and analyzed and the predicted infrared intensities and Raman activities are reported.
66 citations
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TL;DR: The molecule (O, N donor ligand) is thought to adsorb through the carboxyl oxygen atom with the benzene ring in a 'perpendicular side on orientation' with respect to the silver surface.
64 citations
Cited by
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01 Feb 1995
TL;DR: In this paper, the unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio using DFT, MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set.
Abstract: : The unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio. Harmonic force fields are obtained using Density Functional Theory (DFT), MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set. DFT calculations use the Local Spin Density Approximation (LSDA), BLYP, and Becke3LYP (B3LYP) density functionals. Mid-IR spectra predicted using LSDA, BLYP, and B3LYP force fields are of significantly different quality, the B3LYP force field yielding spectra in clearly superior, and overall excellent, agreement with experiment. The MP2 force field yields spectra in slightly worse agreement with experiment than the B3LYP force field. The SCF force field yields spectra in poor agreement with experiment.The basis set dependence of B3LYP force fields is also explored: the 6-31G* and TZ2P basis sets give very similar results while the 3-21G basis set yields spectra in substantially worse agreements with experiment. jg
1,652 citations
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TL;DR: Criteria for choosing the optimum isotherm model is established through a critical review of different adsorption models and the use of various mathematically error functions such as linear regression analysis, nonlinear regressionAnalysis, and error functions for adsorption data optimization.
1,151 citations
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TL;DR: An improved synthesis of colloidal gold nanorods (NRs) is reported by using aromatic additives that reduce the concentration of hexadecyltrimethylammonium bromide surfactant to ~0.05 M as opposed to 0.1 M in well-established protocols.
Abstract: We report an improved synthesis of colloidal gold nanorods (NRs) by using aromatic additives that reduce the concentration of hexadecyltrimethylammonium bromide surfactant to ∼0.05 M as opposed to 0.1 M in well-established protocols. The method optimizes the synthesis for each of the 11 additives studied, allowing a rich array of monodisperse gold NRs with longitudinal surface plasmon resonance tunable from 627 to 1246 nm to be generated. The gold NRs form large-area ordered assemblies upon slow evaporation of NR solution, exhibiting liquid crystalline ordering and several distinct local packing motifs that are dependent upon the NR’s aspect ratio. Tailored synthesis of gold NRs with simultaneous improvements in monodispersity and dimensional tunability through rational introduction of additives will not only help to better understand the mechanism of seed-mediated growth of gold NRs but also advance the research on plasmonic metamaterials incorporating anisotropic metal nanostructures.
748 citations
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TL;DR: The surface plasmon resonance (SPR) and photoemission properties of Ag nanoparticles are found to be sensitive tocitrate concentration and a blue shift in SPR and an enhancement in photoluminescence intensity are observed with increase in citrate concentration.
373 citations