Surface vibrational spectroscopy reflection-absorption infrared spectra

With these favorable circumstances, the HREEL spectrum of poiyimide reveals a large number of vibrational bands, quite well resolved from each other. In order to help band assignments, IR transmission spectrum, or Fourier Transform IRAS (Infrared Reflection Absorption Spectroscopy) spectra, from model ODA, PMDA and PMDA-ODA surfaces can be used. These last spectral data have been superimposed on the HREEL spectrum, in the 1000-2(XX) cm i region, where a number of vibrational bands do signiflcandy overlap (Fig. 2). It is quite clear that all the different chemical sites have their fingerprints t... 

Although optical vibrational techniques are less sensitive than electron-based spectro-metric methods, these techniques are employed extensively for thin-film characterization because of the specific and characteristic vibrational spectrum shown by various functional groups and molecules present in the film. The most commonly used vibrational spectroscopic techniques are infrared (IR) and Raman spectroscopy. Because of the interference caused by absorption of IR by the underlying substrate, IR reflection-adsorption spectroscopy (IRRAS) and its polarization modulation (PM) analog, PM-IRRAS, which uses the polarization selectivity of surface adsorption, are typically employed to characterize thin films (Gregoriou and Rodman, 2006). 

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