External reflection, spectroscopy ellipsometry

Characterization of these structures can be accomplished using a number of techniques, with the most useful being XPS [45], polarized infrared external reflectance spectroscopy (PIERS) [46-48], measurement of contact angles, ellipsometry [49,50] and, increasingly, STM/AFM [51-54]. Computation has also been very useful in understanding the order in these structures [55, 56]... 

Polyimide surface modification by a wet chemical process is described. Poly(pyromellitic dianhydride-oxydianiline) (PMDA-ODA) and poly(bisphenyl dianhydride-para-phenylenediamine) (BPDA-PDA) polyimide film surfaces are initially modified with KOH aqueous solution. These modified surfaces are further treated with aqueous HC1 solution to protonate the ionic molecules. Modified surfaces are identified with X-ray photoelectron spectroscopy (XPS), external reflectance infrared (ER IR) spectroscopy, gravimetric analysis, contact angle and thickness measurement. Initial reaction with KOH transforms the polyimide surface to a potassium polyamate surface. The reaction of the polyamate surface with HC1 yields a polyamic acid surface. Upon curing the modified surface, the starting polyimide surface is produced. The depth of modification, which is measured by a method using an absorbance-thickness relationship established with ellipsometry and ER IR, is controlled by the KOH reaction temperature and the reaction time. Surface topography and film thickness can be maintained while a strong polyimide-polyimide adhesion is achieved. Relationship between surface structure and adhesion is discussed. 

FTIR gives important molecular information on the species formed on the electrode surface [186,233,271,274,288,290,305,328,332,334,349-361], IR radiation is strongly absorbed by most organic solvents and particularly by water, which distinguishes it from the UVATS radiation used in these spectroscopies and also in ellipsometry. This leads inevitably to the use of a thin-layer cell in transmittance mode however, the severe attenuation of the IR beam still remains a serious problem. Therefore, in the majority of cases internal or external reflection techniques have been applied. 

One interesting aspect of the application of IR spectroscopy relates to thin (micrometer) and ultrathin (<50 nm) polymer films, polymer surfaces, and polymer-substrate interfaces [23]. So-called external reflection methods can be used to determine the important properties of thin films (comprising monolayers and multilayers) such as thickness, anisotropy, molecular orientation, and composition. The most frequently applied methods include IR ellipsometry (IRE) [63-67] and IR reflection absorption spectroscopy (IRRAS), which may also be referred to as reflection absorption infrared spectroscopy (RAIRS) [1,23]. 

Although there are many methods available to determine e(ar) for a crystal from spectra of transmissivity, external reflection, ellipsometry, etc., they are in general nonversatile and useful only for a limited range of optical constants. The advantage of surface polariton spectroscopy is that it provides a direct... 

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