Polarized XANES studies of oriented polyethylene and fluorinated polyethylenes

Ohta, Toshiaki; Seki, Kazuhiko; Yokoyama, Toshihiko; Morisada, Ikuo; Edamatsu, Kunishige

doi:10.1088/0031-8949/41/1/036

Cited by 119 publications

(89 citation statements)

References 15 publications

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“…By use of a synchrotron radiation, they observed anisotropic absorp-tion spectra with an incident beam normal or near parallel to the film plane and identified 284.9 eV peak as a Cls---+n* transition. Since then, studies of core electron absorption spectra of polymers gradually increased in number: polyethylene, 18 • 19 polytetrafluoroethylene, 18 poly(vinylidene fluoride), 18 polyimide, 20 poly( dimethyl phenylene oxide), 20 poly(vinyl methyl keton), 20 etc. have been made for various purposes.…”

mentioning

confidence: 99%

Core Electron Absorption Spectra of Poly(ethylene terephthalate) and Poly(ethylene 2,6-naphthalate) Films

Ouchi

Nakai

Kamada

et al. 1995

Polym J

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ABSTRACT:Absorption spectra by means of the transmission method and total electron yield method were obtained for poly(ethylene terephthalate) (PET) and poly(ethylene 2,6-naphthalate) (PEN) films in the soft X-ray region by use of synchrotron radiation. The absorptions at 285.6 and 289.3 eV were due to Cls->n* transitions, showing stronger intensities for obliquely incident light than for normal. Broad absorptions consisting of humps at 293.5, 296.9, and 304.5 eV were originated in Cls->cr* transitions, having stronger intensities for an incident beam normal to the film plane than for oliquely incident light. The strong absorption of core electrons of oxygen appeared near 540.5 eV and was attributed to an Ols--.cr* transition; a neighboring peak at 532.3 eV was sensitive to the incident angle and was assigned as O!s--.n* transition. Oscillator strength and other optical features are briefly discussed. KEY WORDSPolarized Absorption Spectra / Synchrotron Radiation / Poly(ethylene terephthalate) / Poly(ethylene naphthalate) / Biaxially Oriented Films/ Total Electron Yield/ Transmission / Carbon K Edge/ Oxygen K Edge / Oscillator Strength / Absorption and em1ss10n spectra of the valence electrons of poly(ethylene terephthalate) (PET) have been studied for the clarification of photochemical and photophysical features. 1 -10 The polarized absorption and reflection spectra of uniaxially drawn PET films were analyzed in detail in the ultraviolet region down to 190 nm (or up to about 6.5 eV); the transition energies observed therein were compared with theoretical values from molecular orbital calculations. 8 -i O The emission spectra were measured and their origins were discussed. 4 -8 • 1° Furthermore, X-ray photoelectron spectrum of the valence band of PET in the binding energy up to about 30 e V was obtained by use of synchrotron radiation, together with simulation calculations 11 • 12 ; conformational effects were revealed in the spectra. 12 The spectroscopy related to the core electrons, whose energy corresponds to far ultraviolet or soft X-ray, has been studied for PET by means of X-ray photoelectron spectroscopy (XPS); whereby, assignments were given for three kinds of carbon ( carbonyl, aromatic, and aliphatic) and two kinds of oxygen (carbonyl and ester). 12 -15 Recently, electron energy loss spectroscopy (EELS) was applied to PET 16 ; spectral features of this polymer were discussed with the aid of core excitation spectra of small molecule analogues and extended Ruckel molecular orbital calculations of dimethylterephthalate.Absorption spectra of core electrons of polymers were first obtained by Seki et a/ 1 7 for very thin oriented syndiotactic 1,2-polybutadiene films. By use of a synchrotron radiation, they observed anisotropic absorp-127

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confidence: 99%

Core Electron Absorption Spectra of Poly(ethylene terephthalate) and Poly(ethylene 2,6-naphthalate) Films

Ouchi

Nakai

Kamada

et al. 1995

Polym J

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“…To explore this possibility we assume that XAS from oriented polyethylene (PE) and benzene provide useful approximations for anisotropic XAS from the backbone and phenyl rings, respectively. XAS from oriented (stretched) PE reveals a very pronounced imbalance of spectral weight in the σ1* over the σ2* region when is oriented along the chain axes [46,47]. It is also evident that the σ* contributions in PE are not simply distributed in the two σ1* and σ2* lines of the above model; rather, the σ1* region of our model is split into several features in PE XAS [42,48].…”

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confidence: 66%

Molecular anisotropy effects in carbonK-edge scattering: Depolarized diffuse scattering and optical anisotropy

Stone

Kortright

2014

Phys. Rev. B

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Some polymer properties, such as conductivity, are very sensitive to short-and intermediaterange orientational and positional ordering of anisotropic molecular functional groups, and yet means to characterize orientational order in disordered systems are very limited. We demonstrate that resonant scattering at the carbon K-edge is uniquely sensitive to short-range orientation correlations in polymers through depolarized scattering at high momentum transfers, using atactic polystyrene as a well-characterized test system. Depolarized scattering is found to coexist with unpolarized fluorescence, and to exhibit pronounced anisotropy. We also quantify the spatially averaged optical anisotropy from low-angle reflectivity measurements, finding anisotropy consistent with prior visible, x-ray absorption, and theoretical studies. The average anisotropy is much smaller than that in the depolarized scattering and the two have different character. Both measurements exhibit clear spectral signatures from the phenyl rings and the polyethylene-like backbone. Discussion focuses on analysis considerations and prospects for using this depolarized scattering for studies of disorder in soft condensed matter.

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“…That is, the C-C chains of PTFE are nearly parallel to the substrate surface. Nagayama et al reported that the C-C chains of PTFE in a film of 100 nm thickness are almost parallel to the substrate, based on C K-edge NEXAFS spectra [9] . Our results show a very similar trend to their results.…”

Section: Resultsmentioning

confidence: 99%

“…Near-edge X-ray absorption fine structure (NEXAFS) spectroscopy is also known to be a powerful tool for investigating the molecular orientation [8] . The polarization dependence of NEXAFS spectra for the carbon and fluorine K-edge regions of PTFE at room temperature has previously been measured and peak assignments were proposed [9] . Nagayama et al studied mechanical rubbing effects on PTFE using NEXAFS [10,11] .…”

Section: Introductionmentioning

confidence: 99%

Effects of annealing on the molecular orientation in polytetrafluoroethylene thin films

Kobayashi¹,

Okudaira

Okajima³

2012

Surface & Interface Analysis

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aThe effects of annealing on the molecular orientation in polytetrafluoroethylene (PTFE) thin films evaporated on copper and silicon plates were studied using F K-edge near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. The intensity of the F 1 s ! s*(C-F) transition in the NEXAFS spectrum from a non-annealed PTFE thin film on a copper plate at a glancing X-ray incidence angle was stronger than that at the normal incidence angle. For a thin film annealed at~250 C in a nitrogen atmosphere, the s*(C-F) peak intensity at the glancing angle was weaker than that at a normal angle. The F K-edge NEXAFS spectra of a thin film annealed at~350 C showed a weakening dependence on the X-ray incidence angle. This result indicates that the molecules in a PTFE thin film are increasingly oriented normal to the substrate surface with increasing annealing temperature and are oriented randomly.

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Polarized XANES studies of oriented polyethylene and fluorinated polyethylenes

Cited by 119 publications

References 15 publications

Core Electron Absorption Spectra of Poly(ethylene terephthalate) and Poly(ethylene 2,6-naphthalate) Films

Core Electron Absorption Spectra of Poly(ethylene terephthalate) and Poly(ethylene 2,6-naphthalate) Films

Molecular anisotropy effects in carbonK-edge scattering: Depolarized diffuse scattering and optical anisotropy

Effects of annealing on the molecular orientation in polytetrafluoroethylene thin films

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