Infrared spectroscopy structure correlation studies

In the current study, we tested the applicability of near infrared spectroscopy coupled with correlation analysis to quantitation of the dependence of montmorillonite spectra on two of the structural features known to be of importance in clay surface chemistry -hydration and exchangeable iron. These clays were... 

Corkill et al. [56] have used for the first time the infrared spectroscopy for foam films. The measurement of the adsorption of the infrared light provides information about the water content in the foam films which is of major significance for the black foam films. These studies involved the use of dispersion type instruments. In order to obtain measurable values of adsorption, the infrared light is passed through a series of vertical films (up to 10) formed in a cylindrical tube acting as a frame. Additional information about the film structure the authors derived from the correlation between the optical infrared transmission data and the film reflectance measurements. Here a three-layer model of the film structure consisting of an aqueous core sandwiched between two adsorption layers is assumed (see Section 2.1.3). 

Infrared spectroscopy may be used to investigate conjugated polymers in much the same way as Raman spectroscopy. Both methods make it possible to analyze chemical structures, to study dynamical processes such as cis-trans isomerization, or to investigate the doping process. However, because of the missing correlation between electronic and vibronic transitions, the infrared scenario is less colorful. For instance, no shift of IR active modes indicating particular structural defects of the polymer backbone has yet been observed. 

The mean vibrational structure (structure V) is that obtained with an exposure time of the same order of magnitude as the vibrational correlation time Ty (Ty —10 s is the time scale of infrared and Raman spectroscopy ). Recently, time-averaged molecular dynamics experiments have allowed a statistical study of this type of structure. 

Resonant raman spectroscopy has proved to be another valuable tool for the study of the structure of the polydiacetylene chain. Due to the resonance enhancement the spectra are compared to greatly simplified, infrared spectra and show as principle feature only the in-plane modes of the polymer chain. The correlation of the CsC and C = C stretching modes and their temperature dependence have been interpreted as resonances between the mesomeric structures (I) and (II) i32) Hoy(rever, a model using simple anharmonic force constants for the acetylene structure (II) is in good agreement with the experiment, e.g, the temperature and pressure dependence of the vibration frequency and the mechanical properties... 

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