Surface characterization reflectance techniques

Infrared reflection techniques are used for surface characterization because they provide highly detailed information about the molecular structure, orientation on... 

There are several major areas of interfacial phenomena to which infrared spectroscopy has been applied that are not treated extensively in this volume. Most of these areas have established bodies of literature of their own. In many of these areas, the replacement of dispersive spectrometers by FT instruments has resulted in continued improvement in sensitivity, and in the interpretation of phenomena at the molecular level. Among these areas are the characterization of polymer surfaces with ATR (127-129) and diffuse reflectance (130) sampling techniques transmission IR studies of the surfaces of powdered samples with adsorbed gases (131-136) alumina(137.138). silica (139). and catalyst (140) surfaces diffuse reflectance studies of organo- modified mineral and glass fiber surfaces (141-143) metal overlayer enhanced ATR (144) and spectroelectrochemistry (145-149). 

Boujday S, Methivier C, Beccard B, Pradier C-M (2009) Innovative surface characterization techniques applied to immunosensor elaboration and test comparing the efficiency of Fourier transform-surface plasmon resonance, quartz crystal microbalance with dissipation measurements, and polarization modulation-reflection absorption infrared spectroscopy. Anal Biochem 387 194-201... 

A problem that may be encountered when analyzing a solid sample by transmittance spectroscopy is radiation scattering. Employing reflectance spectroscopy can sometimes reduce this problem. With this technique, the infrared spectra of most solid materials are easily obtained with little or no sample preparation. Spectra of a wide range of solid samples can be characterized with this technique, such as coatings on beverage containers and silicon wafers, polymer films, or other intractable samples. The reflectance technique, however, is less sensitive than the transmittance technique since about 80 /o of the infrared radiation is lost after being reflected off the sample surface. 

In the majority of reports on the spectroscopic characterization of surface hydroxyls, the analysis of the spectra is restricted to the v(O-H) region. Occasionally, the assignments are supported by analysis of the deformation modes, but these are usually masked by bulk absorption of the sample. Additional helpful information can be obtained from the overtones and combination modes. Unfortunately, the according bands are of low intensity and occur at high frequencies where noise becomes relevant in transmission spectra. Advantageous in this respect is the diffuse reflectance technique but it renders quantification extremely difficult. 

Surface characterization by spectroscopic techniques yields information on the functional groups and elemental composition on the surface of polymeric biomaterials. The most common spectroscopic tools used for biomedical polymers are X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), secondary ion mass spectrometry (SIMS), and Fourier transform infrared spectroscopy (FTIR) (diffuse reflectance and attenuated total internal reflectance modes). Each of these techniques is discussed in the succeeding text. 

The most common infrared sampling techniques used to examine paint samples are attenuated total reflectance and photoacoustic spectroscopies. Liquid paints, dried films and paint chips may all be investigated in this way. Depth profiling can be useful when examining paint, as the surface properties will vary importantly from the bulk properties. In addition, most paint films contain two or more layers with different compositions, and so reflectance techniques are necessary for the characterization of individual layers. 

Infrared spectroscopy, including Fourier-transform infrared (FTIR) spectroscopy, is one of the oldest and most widely used analytical techniques in adhesion-related research. Transmission infrared spectroscopy has been used to identify compounds used in formulating adhesives and to follow curing reactions. Attenuated total reflection (ATR) (see Infrared spectroscopy attenuated total reflection) has been used to probe the surface composition of polymers that have been surface modified by an etching process or by deposition of a film. More recently, reflection-absorption infrared spectroscopy (see Infrared spectroscopy RAIR) has been used to characterize thin films on the surfaces of reflecting substrates. 

Surface science. Surface characterization studies included those for base polyurethane segmented block copolymers and base polymer modified by <2 wt% U-P[AB], Surface analytical techniques included tapping mode atomic force microscopy (TM-AFM), X-ray photoelectron spectroscopy (XPS), wetting behavior by dynamic contact angle (DCA) analysis and sessile drop measurements, and attenuated total reflectance infrared spectroscopy (ATR-IR). Contact antimicrobial behavior of U-P[AB] containing hydantoin and aikylammonium B side chains was determined by spray-on and sandwich tests previously described in detail elsewhere [11, 22, 38]. 

Fundamental for the characterization of polymer grafting surface are microscopy techniques, i.e. Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Attenuated Total Reflection-Eourier transform infrared spectroscopy (ATR-FTIR spectroscopy). 

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