Entity

Time filter

Source Type

Puducherry, India

Prabhu T.,Avc College | Periandy S.,Tagor Arts College | Mohan S.,Hawassa University
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy | Year: 2011

A combined experimental and theoretical study on molecular and vibrational structure of 2,3-dimethyl naphthalene (2,3-DMN) has been undertaken in the present work. The FTIR and FT Raman spectra of 2,3-DMN were recorded in the region 4000-100 cm-1. The optimized geometries were calculated by HF and DFT (B3LYP) methods with 6-31++G (d, p), 6-311G (d, p) and 6-311++G (d, p) basis sets. The harmonic vibrational frequencies, infrared intensities and Raman activities of the 2,3-DMN were evaluated with these methods. After scaling the computational wave numbers are in very good agreement with the experimental values. A detailed interpretation of the infrared and Raman spectra of 2,3-DMN is presented. The effects of substitution of methyl group on the molecule have also been discussed. © 2010 Elsevier B.V. All rights reserved. Source


Ramalingam S.,Avc College | Ramalingam S.,University | Periandy S.,Tagor Arts College
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy | Year: 2011

In the present study, the FT-IR and FT-Raman spectra of 4-chloro-2-methylaniline (4CH2MA) have been recorded in the range of 4000-100 cm-1. The fundamental modes of vibrational frequencies of 4CH2MA are assigned. All the geometrical parameters have been calculated by HF and DFT (LSDA, B3LYP and B3PW91) methods with 6-31G (d, p) and 6-311G (d, p) basis sets. Optimized geometries of the molecule have been interpreted and compared with the reported experimental values for aniline and some substituted aniline. The harmonic and anharmonic vibrational wavenumbers, IR intensities and Raman activities are calculated at the same theory levels used in geometry optimization. The calculated frequencies are scaled and compared with experimental values. The scaled vibrational frequencies at LSDA/B3LYP/6-311G (d, p) seem to coincide with the experimentally observed values with acceptable deviations. The impact of substitutions on the benzene structure is investigated. The molecular interactions between the substitutions (Cl, CH 3 and NH2) are also analyzed. © 2010 Elsevier B.V. Source


Ramalingam S.,Avc College | Periandy S.,Tagor Arts College | Elanchezhian B.,Avc College | Mohan S.,Center for Research and Development
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy | Year: 2011

FT-IR (4000-100 cm-1) and FT-Raman (4000-100 cm-1) spectra of solid sample of 4-chloro-2-fluoro toluene (4Cl2FT) have been recorded using Bruker IFS 66 V spectrometer. Ab initio-HF (HF/6-311++G (d, p)) and DFT (B3LYP/6-311++G and B3PW91/6-311++G (d, p)) calculations have been performed giving energies, optimized structures, harmonic vibrational frequencies, depolarization ratios, IR intensities, Raman activities. The vibrational frequencies are calculated and scaled values are compared with FT-IR and FT-Raman experimental values. The isotropic HF and DFT analyses showed good agreement with experimental observations. The differences between the observed and scaled wave number values of most of the fundamentals are very small in B3LYP than HF. Comparison of the simulated spectra provides important information about the ability of the computational method (B3LYP) to describe the vibrational modes. The influences of substitutions on the geometry of molecule and its normal modes of vibrations have also been discussed. The changes made by substitutions on the benzene are much responsible for the non-linearity of the molecule. This is an attractive entity for the future studies of non-linear optics. © 2010 Elsevier B.V. All rights reserved. Source


Prabhu T.,Avc College | Periandy S.,Tagor Arts College | Ramalingam S.,Avc College
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy | Year: 2011

The FT-IR and FT-Raman spectra of m-Xylol molecule have been recorded using Bruker IFS 66 V spectrometer in the range 4000-100 cm -1. The molecular geometry and vibrational frequencies in the ground state are evaluated using the Hartree-fock (HF) and B3LYP with 6-31+G (d, p), 6-31++G (d, p) and 6-311++G (d, p) basis sets. The computed frequencies are scaled using a suitable scale factors to yield good agreement with the observed values. The HF and DFT analysis agree well with experimental observations. Comparison of the fundamental vibrational frequencies with calculated results by HF and B3LYP methods indicate that B3LYP/6-311++G (d, p) is superior to HF/6-31+G (d, p) for molecular vibrational problems. The complete data of this title compound provide some useful information for the study of substituted benzenes. The influences of Methyl groups on the geometry of benzene and its normal modes of vibrations have also been discussed. © 2011 Elsevier B.V. All rights reserved. Source

Discover hidden collaborations