High-Resolution FTIR Microspectroscopy of Thin Films

In all cases, the ATR method gives poor SNR for hard, coarse particles. For these objects, DT or DR is preferable. 

A CIRCLE cell can be used in studies of ultrathin films on fibers (Fig. 4.14) [180]. Comparing spectra recorded for the fibers that are (a) aligned along and (b) coiled around a cylindrical IRE provides information abont orientation of surface species with respect to the fiber axis. This is because fibers are highly crystalline, and as IR radiation passes through them, it becomes polarized in parallel and perpendicular directions. As a result, the absorption bands due to the modes with different TDMs with respect to the fiber surface have different intensities for the two positions of the fibers with respect to the IRE. 

HIGH-RESOLUTION FTIR MICROSPECTROSCOPY OF THIN FILMS 

FTIR microspectroscopy (or FTIR microscopy or /r-FTIR) has been a conventional method for materials characterization since 1984, when Analect Instruments (now KVB) introduced a transmission microscope interfaced to its AQS FTIR [181]. Since then, FTIR microspectroscopy has developed into a greatly advanced tool for the analysis of thin films on a wide variety of snbstrates (including a single particle, cell, bacterium, or fiber) for scientific, industrial, and forensic applications [182-I9I]. Examples include oxide layers on technical Si wafers [192], organic films on Si (001) [193], organic [194-196] 

For illustration. Fig. 4.35 (curves 1 and 2) shows the transmission spectra of a 0.1-tim-thick film of an epoxy resin taken from different sampling areas. 

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HIGH-RESOLUTION FTIR MICROSPECTROSCOPY OF THIN FILMS 343... 

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