Fermi resonances and vibrational spectra of crystalline and amorphous polyethylene chains

Abbate, Sergio; Zerbi, G.; Wunder, Stephanie L.

doi:10.1021/j100213a017

Cited by 126 publications

(102 citation statements)

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“…An increase in the intermolecular interaction and, therefore, formation of clusters or a crystalline structure of DODAB molecules is also revealed by the increase of the asymmetry of the symmetric stretching vibration at 2848 cm −1 [12][13][14]. As it can be seen from Fig.…”

Section: Discussionmentioning

confidence: 80%

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Characterization of the structure of modified clay by Raman spectroscopy

et al. 2005

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One of promising fillers for polymers, sodium montmorillonite modified by dioctadecyldimethylammonium bromide (DODAB), has been studied by Raman spectroscopy, X-ray analysis, and differential scanning calorimetry (DSC). It has been shown that an increase in the DODAB content enlarges the height of a clay interlayer space through filling the clay interlayer galleries with DODAB molecules. According to both Raman and DSC data, DODAB molecules grafted to the clay can be in three different phase states depending on the modifier content. At a low DODAB content, its molecules are separated and contain a significant amount of gauche-conformers in methylene chains. At a medium content, the DODAB molecules form clusters, and the amount of trans-conformers in the DODAB methylene chains considerably increases. At a high DODAB content, its molecules are straightened and form a 2D ordered structure with either hexagonal or triclinic symmetry.Computer-simulated schematic structure of the interlayer space of Na + -montmorillonite modified by DODAB

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Section: Discussionmentioning

confidence: 80%

“…The second reason is an enhancement of the symmetric stretching vibration at 2848 cm −1 located side-by-side. This enhancing is directly connected with the increase in the amount of gauche-conformers and disordering of molecular packing [12][13][14]. Looking at the spectra in Fig.…”

Section: Discussionmentioning

confidence: 91%

Characterization of the structure of modified clay by Raman spectroscopy

et al. 2005

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“…While in the stretching region the effect of the crystal packing cannot be easily recognized because of the small crystal splitting and to the complex band structure (ascribed to the occurrence of Fermi resonances 37,38 ), bending and rocking peaks show indeed the characteristic splitting into two IR active components, of comparable intensity.…”

Section: The Ir Spectrum Of Polyethylene: a Short Reviewmentioning

confidence: 99%

Intermolecular modulation of IR intensities in the solid state. The role of weak interactions in polyethylene crystal: A computational DFT study

Galimberti

Milani

Maschio

et al. 2016

The Journal of Chemical Physics

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Density functional crystal orbital study on the normal vibrations and phonon dispersion curves of all-trans polyethylene J. Chem. Phys. 108, 7901 (1998) Density functional theory calculations with periodic boundary conditions are exploited to study the infrared spectrum of crystalline polyethylene. Spectral changes lead by the intermolecular packing in the orthorhombic three-dimensional crystal are discussed by means of a careful comparison with calculations carried out for an isolated polymer chain in the all-trans conformation, described as an ideal one-dimensional crystal. The results are analyzed in the framework of the "oligomer approach" through the modelling of the IR spectrum of n-alkanes of different lengths. The study demonstrates that a relevant absorption intensity modulation of CH 2 deformation transitions takes place in the solid state. This finding suggests a new interpretation for the experimental evidences collected in the past by means of IR intensity measurement during thermal treatment. Moreover, the comparison between calculations for 3-D crystal and for the isolated polyethylene chain (1-D crystal) allows to put in evidence the effect of the local electric field on the computed infrared intensities. This observation provides guidelines for the comparison between infrared absorption intensities predicted for an isolated unit and for a molecule belonging to a crystal, through the introduction of suitable correction factors based on the refraction index of the material and depending on the dimensionality of such units (0D-molecule; 1D-polymer; 2D-slab). Published by AIP Publishing.[http://dx

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“…However, some authors report the occurrence, effects and details of FR involving the CH 2 symmetric stretch fundamental and the 1st overtone of the CH 2 scissors mode and collectively argue and present a consensus that FR is a standard feature of hydrocarbon chain vibrational spectra [34][35][36][37][38]. These two modes are of the same symmetry species, A, and can thus interact through FR [39].…”

Section: C-h Stretchesmentioning

confidence: 99%

FTIR spectroscopy of synthesized racemic nonacosan-10-ol: a model compound for plant epicuticular waxes

Coward

2010

J Biol Phys

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As there are no published graphically presented, detailed IR spectra of nonacosan-10-ol (occurring naturally and widely in plant epicuticular waxes of nanotube form), near IR FTIR spectroscopy (fundamentals, overtones and combinations) has been performed on laboratory synthesized racemic nonacosan-10-ol, as a crystalline solid on Mylar, and polypropylene substrates. Room temperature, in vacuo data are presented graphically, in full, and show evidence of extensive hydrogen bonding, an orthorhombic perpendicular subcell, a methylene wagging progression, diagnostic of all-trans conformational order, and Fermi resonance. Moderate or stronger anharmonicity is confirmed. Detailed discussion, quantitative in parts, is given of the observed spectral features, especially as to how they inform crystal structure and molecular conformation, and assignments given for some of the features. The results will serve as a reference for future IR studies of the natural epicuticular wax nanotube form of (S)-nonacosan-10-ol.

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Fermi resonances and vibrational spectra of crystalline and amorphous polyethylene chains

Cited by 126 publications

References 1 publication

Characterization of the structure of modified clay by Raman spectroscopy

Characterization of the structure of modified clay by Raman spectroscopy

Intermolecular modulation of IR intensities in the solid state. The role of weak interactions in polyethylene crystal: A computational DFT study

FTIR spectroscopy of synthesized racemic nonacosan-10-ol: a model compound for plant epicuticular waxes

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