Mesure de l'orientation des polymères en dichroïsme linéaire infrarouge par modulation de polarisation : procédure expérimentale et analyse quantitative

Buffeteau, T.; Desbat, Bernard; Pézolet, Michel; Turlet, JM

doi:10.1051/jcp/1993901467

Cited by 43 publications

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“…3,25 The optical anisotropy in the polymer films was induced in situ using either a polarized Ar + laser (λ ) 514.5 nm) in the Nicolet optical setup or a polarized frequency-doubled Nd:YAG laser (λ ) 532 nm) in the Bomem optical setup. In the two cases, the angle between the laser and the infrared beam was 20°.…”

Section: Methodsmentioning

confidence: 99%

“…Since T 0 is not equal to 1.0 for the infrared bands in photoinduced orientation studies, the T 2 parameter determined by PM-IRLD does not correspond to the order parameter P 2 (cos θ) as opposed to results obtained on molecular orientation studies in stretched polymer samples. 25 Quantitative Analysis of the Orientation and Relaxation Processes. In functionalized polymers, Natansohn et al 2,41,42 have shown that the time dependence of the birefringence during the orientation and relaxation periods can be quite well described by biexponential functions.…”

Section: Methodsmentioning

confidence: 99%

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Photoinduced Orientation of Azobenzene Chromophores in Amorphous Polymers As Studied by Real-Time Visible and FTIR Spectroscopies

et al. 1998

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ABSTRACT:In situ dynamical study of the photoinduced orientation of the DR1 azobenzene derivative in a doped PMMA matrix and in p(DR1A-co-MMA) copolymers was carried out using real-time visible and infrared spectroscopies. The different mechanisms occurring during the photoisomerization cycles were highlighted by following the time dependence of the normalized average absorbance (T 0), the normalized linear dichroism (T2) and the order parameter (P2) during the orientation (laser on) and the relaxation (laser off) periods. The thermal cis-trans back-relaxation and the angular redistribution were followed separately from the T0 and T2 relaxation curves, respectively. The orientation and relaxation curves were fitted by the Kohlrausch-Williams-Watts (KWW) function in order to compare the rate constant and the distribution width for various samples. On one hand, the chromophore-matrix interactions were investigated in doped systems by changing the tacticity of the PMMA matrix. On the other hand, the chromophore-chromophore interactions in functionalized polymers were studied by changing the concentration of azobenzene units in copolymer systems.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Photoinduced Orientation of Azobenzene Chromophores in Amorphous Polymers As Studied by Real-Time Visible and FTIR Spectroscopies

et al. 1998

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“…However, this differential absorption spectrum needs to be further processed to provide a more meaningful quantitative analysis. It can be shown [6] that from the ratio T ratio ¼ T k À T ? =T k þ T ?…”

Section: Resultsmentioning

confidence: 99%

“…Two procedures were proposed in the literature where one employs scaling of the raw polarization modulation spectrum to a polarization modulation spectrum of a polarizer, replacing the sample, oriented parallel to the polarizer preceding the photoelastic modulator [5]. The other one involves two measurements of a polarizer in the sample position in parallel and perpendicular orientations [6]. In Fig.…”

Section: Resultsmentioning

confidence: 99%

“…It relies on a photoelastic modulator (PEM) which modulates the polarization of the IR beam at a high frequency (e.g., 100 kHz) and yields the direct measurement of a spectrum which is related to the dichroic difference spectrum [6]. This method was applied to the investigation of microscopic VLD achieving a spatial resolution down to 20 or 30 lm [7].…”

Section: Introductionmentioning

confidence: 99%

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Microspectroscopic observation of vibrational linear dichroism using polarization-modulated infrared synchrotron radiation

Schmidt

Schade

Grunze

2006

Infrared Physics & Technology

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Linear Dichroism in Infrared Spectroscopy

Buffeteau

Pézolet

2001

Handbook of Vibrational Spectroscopy

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The absorption of linearly polarized infrared radiation by oriented samples is sensitive to the state of polarization of the incident radiation. This phenomenon is known as the infrared linear dichroism (IRLD). The degree of optical anisotropy in oriented samples can be characterized by measuring two spectra using light polarized parallel and perpendicular to a reference direction. In this chapter, the theoretical expressions allowing the quantitative determination of molecular orientation from IRLD measurements for systems showing both uniaxial and biaxial symmetry of orientation are described. In addition, typical examples of the use of IRLD to determine the orientation of polymers and biological membranes are presented. These results were obtained from either static measurements using normal or oblique incidence or dynamic measurements using a rotating polarizer or a photoelastic modulator (PM‐IRLD). The high sensitivity of PM‐IRLD allows following the kinetics of orientation over a short timescale.

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Mesure de l'orientation des polymères en dichroïsme linéaire infrarouge par modulation de polarisation : procédure expérimentale et analyse quantitative

Cited by 43 publications

References 0 publications

Photoinduced Orientation of Azobenzene Chromophores in Amorphous Polymers As Studied by Real-Time Visible and FTIR Spectroscopies

Photoinduced Orientation of Azobenzene Chromophores in Amorphous Polymers As Studied by Real-Time Visible and FTIR Spectroscopies

Microspectroscopic observation of vibrational linear dichroism using polarization-modulated infrared synchrotron radiation

Linear Dichroism in Infrared Spectroscopy

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