DYNAMIC INFRARED LINEAR DICHROISM

I. Noda, A.E. Dowrey and C. Marcott, Characterization of polymers using polarization-modulation infrared techniques Dynamic infrared linear dichroism (DIRLD) spectroscopy. 

Poly(phenoxy phenylene vinylene)(PO-PPV) is synthesized via the chlorine precursor route as shown in Figure 3. The CPR is preferred for preparation of precursor polymers with large substituents such as phenoxy. The precursor film is quite flexible and dynamic infrared linear dichroism (DIRLD) studies (stretching the polymer while recording the dynamic infrared spectra) are in progress. 

Noda, L Dowrey, A. E. Marcott, C., Characterization of Polymers Using Polarization-Modulation Infrared Techniques Dynamic Infrared Linear Dichroism (DIRLD) Spectroscopy. In Fourier Transform Infrared Characterization of Polymers, Ishida, H., Ed. Plenum Press New York, 1987 pp 33-57. 

Figure 1-3. Schematic diagram of the dynamic infrared linear dichroism (DIRLDi experiment 23], A small-amplitude sinusoidal strain is applied to a sample, and submolecular level reorientation responses of chemical moieties are monitored with a polarized IR beam.

Ultimate dichroic ratio Dynamic infrared linear dichroism Observation period Time... 

DYNAMIC INFRARED LINEAR DICHROISM MEASURED WITH A MONOCHROMATOR... 

I. Noda, A. E. Dowrey, and C. Marcott, Characterization of polymers using polarization-modualtion infrared techniques dynamic infrared linear dichroism (DIRLD) spectroscopy, in Fourier-Tran orm Infrared Characterization of Polymers, H. Ishida, Ed., Plenum Press, New York, 1987, p. 33. 

Marcott, C. and Noda, I. (2002) Dynamic infrared linear dichroism spectroscopy. In Handbook of Vibrational Spectroscopy, Vol. 4 (eds J.M. Chalmers and PR. Griffiths), John Wiley Sons, Ltd, Chichester, pp. 2576-2591. 

Up to this poinL we have primarily focused our attention on the application of theo-oprical characterization techniques for monitoring the dynamics of supramolecular stmctures, such as the spatial reorganization of crystals and microphase-separated domains, in various polymeric systems under the influence of flow, deformation, and relaxation. We now shift our attention to rheo-oprical analysis at submolecular scale by using molecular spectroscopic probes. In particular, a rheo-oprical technique called dynamic infrared linear dichroism (DIRLD) spectroscopy, capable of monitoring segmental dynamits of polymer chains, is described. 

Figure 1-3 shows a schematic diagram of a dynamic IR linear dichroism (DIRLD) experiment [20-25] which provided the foundation for the 2D IR analysis of polymers. In DIRLD spectroscopy, a small-amplitude oscillatory strain (ca. 0.1% of the sample dimension) with an acoustic-range frequency is applied to a thin polymer film. The submolecular-level response of individual chemical constituents induced by the applied dynamic strain is then monitored by using a polarized IR probe as a function of deformation frequency and other variables such as temperature. The macroscopic stress response of the system may also be measured simultaneously. In short, a DIRLD experiment may be regarded as a combination of two well-established characterization techniques already used extensively for polymers dynamic mechanical analysis (DMA) [26, 27] and infrared dichroism (IRD) spectroscopy [10, 11]. 

Attenuated total reflection (ATR) FTIR is one of the most useful tools for characterising the chemical composition and physical characteristics of polymer surfaces [53]. One useful application is the measurement of molecular orientation using polarised infrared ATR spectroscopy [54,55]. The polarised infrared ATR spectra normally include three-dimensional (e.g., machine, transverse, and thickness direction) orientational information in contrast to the polarised transmission infrared linear dichroism. In addition, band absorbance of less than 0.7 au is easily achieved, even with the strong absorption bands, because the penetration depth of ATR from sample surfaces can be adjusted to a few micrometers by changing the internal reflection element and/or the angle of incidence. If successful combination of the dynamic infrared spectroscopy and the ATR methods can be achieved, more useful dynamic orientational information can be obtained. 

Probing Metalloproteins Electronic absorption spectroscopy of copper proteins, 226, 1 electronic absorption spectroscopy of nonheme iron proteins, 226, 33 cobalt as probe and label of proteins, 226, 52 biochemical and spectroscopic probes of mercury(ii) coordination environments in proteins, 226, 71 low-temperature optical spectroscopy metalloprotein structure and dynamics, 226, 97 nanosecond transient absorption spectroscopy, 226, 119 nanosecond time-resolved absorption and polarization dichroism spectroscopies, 226, 147 real-time spectroscopic techniques for probing conformational dynamics of heme proteins, 226, 177 variable-temperature magnetic circular dichroism, 226, 199 linear dichroism, 226, 232 infrared spectroscopy, 226, 259 Fourier transform infrared spectroscopy, 226, 289 infrared circular dichroism, 226, 306 Raman and resonance Raman spectroscopy, 226, 319 protein structure from ultraviolet resonance Raman spectroscopy, 226, 374 single-crystal micro-Raman spectroscopy, 226, 397 nanosecond time-resolved resonance Raman spectroscopy, 226, 409 techniques for obtaining resonance Raman spectra of metalloproteins, 226, 431 Raman optical activity, 226, 470 surface-enhanced resonance Raman scattering, 226, 482 luminescence... 

A dynamic linear infrared dichroism study was carried out as a function of temperature on isotropic and cold drawn HDPE using a rapid-scan setup. The dynamic in-phase dichroic spectrum and its components (parallel and perpendicular polarised spectra) were analysed. 15 refs. 

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