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Normal Coordinate Analysis (normal + coordinate_analysis)
Selected AbstractsElectronic and Vibrational Properties of Fluorenone in the Channels of Zeolite LCHEMISTRY - A EUROPEAN JOURNAL, Issue 10 2004André Devaux Dr. Abstract Fluorenone (C13H8O) was inserted into the channels of zeolite L by using gas-phase adsorption. The size, structure, and stability of fluorenone are well suited for studying host,guest interactions. The Fourier transform IR, Raman, luminescence, and excitation spectra, in addition to thermal analysis data, of fluorenone in solution and fluorenone/zeolite L are reported. Normal coordinate analysis of fluorenone was performed, based on which IR and Raman bands were assigned, and an experimental force field was determined. The vibrational spectra can be used for nondestructive quantitative analysis by comparing a characteristic dye band with a zeolite band that has been chosen as the internal standard. Molecular orbital calculations were performed to gain a better understanding of the electronic structure of the system and to support the interpretation of the electronic absorption and luminescence spectra. Fluorenone shows unusual luminescence behavior in that it emits from two states. The relative intensity of these two bands depends strongly on the environment and changes unexpectedly in response to temperature. In fluorenone/zeolite L, the intensity of the 300 nm band (lifetime 9 ,s) increases with decreasing temperature, while the opposite is true for the 400 nm band (lifetime 115 ,s). A model of the host,guest interaction is derived from the experimental results and calculations: the dye molecule sits close to the channel walls with the carbonyl group pointing to an Al3+ site of the zeolite framework. A secondary interaction was observed between the fluorenone's aromatic ring and the zeolite's charge-compensating cations. [source] Analysis of structure and vibrational spectra of 2,5-dihydroxybenzoicacid based on density functional theory calculationsJOURNAL OF RAMAN SPECTROSCOPY, Issue 4 2010V. Krishnakumar Abstract The spectra of 2,5-dihydroxybenzoic acid (DHBA) have been recorded using Fourier transform-infrared spectroscopy (FT-IR) and FT-Raman measurements. The total energy calculations of DHBA were evaluated for various possible conformers. The spectra were interpreted with the help of normal coordinate analysis based on density functional theory (DFT) using standard B3LYP/6,31G* method for the most optimized geometry. The effect of intramolecular hydrogen bonding was discussed. Normal coordinate calculations were performed with the DFT force field corrected by a recommended set of scaling factors, yielding fairly good agreement between observed and calculated frequencies. On the basis of the comparison between calculated and experimental results, assignments of fundamental modes were examined. Copyright © 2009 John Wiley & Sons, Ltd. [source] Density functional theory calculations and vibrational spectra of 2-bromo-4-chloro phenol and 2-chloro-4-nitro phenolJOURNAL OF RAMAN SPECTROSCOPY, Issue 11 2009V. Krishnakumar Abstract FTIR and FT Raman spectra of 2-bromo-4-chloro phenol (BCP) and 2-chloro-4-nitro phenol (CNP) were recorded in the region 4000,400 and 4000,50 cm,1, respectively. The molecular structure, geometry optimization, and vibrational wavenumbers were investigated. The spectra were interpreted with the aid of normal coordinate analysis based on density functional theory (DFT) using the standard B3LYP/6-31G** method and basis set combination and was scaled using multiple scale factors, which yield good agreement between the observed and calculated wavenumbers. The results of the calculations are applied to simulate the infrared and Raman spectra of the title compounds, which showed excellent agreement with the observed spectra. Copyright © 2009 John Wiley & Sons, Ltd. [source] Density functional theory calculations and vibrational spectra of p -bromonitrobenzeneJOURNAL OF RAMAN SPECTROSCOPY, Issue 8 2009V. Krishnakumar Abstract FT-IR and FT-Raman spectra of p -bromonitrobenzene (p-BNB) have been recorded in the region 4000,400 cm,1 and 4000,50 cm,1, respectively. The molecular structure, geometry optimization, vibrational wavenumbers have been investigated. The spectra were interpreted with the aid of normal coordinate analysis based on the density functional theory (DFT) using the standard B3LYP/6-31G method and basis set combination and was scaled using multiple scale factors yielding good agreement between observed and calculated wavenumbers. The results of the calculations are applied to simulate infrared and Raman spectra of the title compound which showed reasonable agreement with the observed spectra. Copyright © 2009 John Wiley & Sons, Ltd. [source] Polarized infrared and Raman spectra of KGd(WO4)2 and their interpretation based on normal coordinate analysisJOURNAL OF RAMAN SPECTROSCOPY, Issue 2 2002L. Macalik The direction of the transition dipole moments for the vibrations of the single WOW and double WOOW oxygen bridges in layered scheelite tungstates is derived from the Polarized infrared and Raman spectra of the KGd(WO4)2 single crystal. Their experimental values are compared with those obtained from the calculated atomic Cartesian displacements for the particular normal modes. The assignment of the IR and Raman bands to the respective molecular vibrations was obtained on the basis of the normal coordinate analysis and potential energy distribution. Copyright © 2002 John Wiley & Sons, Ltd. [source] | ||||||||||