Reflection angle infrared spectroscopy

Of particular interest are the specific chemical interactions that occur between the coupling agent s active functionality and either the metal oxide or the polymeric top-coat. Recently, reflection angle infrared spectroscopy (RAIRS) [12, 13] and... 

Fundamental studies by reflection angle infrared spectroscopy of the bonding of EME coupling agents to metal oxides reveal a significant shift in the carbonyl absorbance band when the coupling agent is applied as a very thin layer on a metal oxide. The shift is reproducible and the extent varies with the type of oxide. These results were obtained both by use of copper mirrors and from CuzO powder coated with very thin layers of model compounds. The compounds were not removable by isopropanol, a solvent for the bulk compound. The thiol absorbances of thin layers of model compounds were also found to decrease in relative intensity with time. This illustrates that a specific chemical interaction has occurred. 

PVIE polyvinyl isobutyl ether RAIR reflection angle infrared spectroscopy... 

Modern methods of vibrational analysis have shown themselves to be unexpectedly powerful tools to study two-dimensional monomolecular films at gas/liquid interfaces. In particular, current work with external reflection-absorbance infrared spectroscopy has been able to derive detailed conformational and orientational information concerning the nature of the monolayer film. The LE-LC first order phase transition as seen by IR involves a conformational gauche-trans isomerization of the hydrocarbon chains a second transition in the acyl chains is seen at low molecular areas that may be related to a solid-solid type hydrocarbon phase change. Orientations and tilt angles of the hydrocarbon chains are able to be calculated from the polarized external reflectance spectra. These calculations find that the lipid acyl chains are relatively unoriented (or possibly randomly oriented) at low-to-intermediate surface pressures, while the orientation at high surface pressures is similar to that of the solid (gel phase) bulk lipid. 

Reflection-Absorption Infrared Spectroscopy (RAIS) operating at the grazing-angle which is one of the most powerful resonance absorption phenomenon and is the most sensitive optical absorption technique available for measuring low concentrations of chemical componnds adhered to surfaces and even allows for the non-destractive mono layer chemical analysis on the surface. Figure 6 shows the FOC-GAP-FTIR spectra 5 and 10 ug/cm 2-CEES deposited as a trace residue on stainless steel surface. It is clear from the spectra shown that low limits of detection (LOD) achievable could be as low as nanograms/cm (milligrams/m ). 

Characterization of the Unmodified and PLL-g-PEG-Modified Surfaces. 3.2.1. RAIRS Measurements of the PLL(20)-g[3.5]-PEG(2) Monolayer. Reflection-absorption infrared spectroscopy (RAIRS) is well suited to study adsorbates on metallic surfaces, which are highly reflective. It relies on reflecting an infrared beam at near-grazing incidence from the metallic surface on which the thin film of interest has been deposited. Only the component of the vibrational transition dipole moments perpendicular to the surface plane contributes to the absorption spectra. The intensity of an absorption band is proportional to the squared cosine of the angle between the transition dipole moment and the surface normal. Therefore, RAIRS provides information not only on fimctional groups but also on orientation and conformation of adsorbed molecules or molecular entities. Metal oxides... 

Infrared external reflection spectroscopy (IR-ERS) is generally based on single external reflection of IR radiation at the surface of a metal or metal film. This method is also called reflection-absorption infrared spectroscopy (RAIRS) or grazing angle... 

The polymer concentration profile has been measured by small-angle neutron scattering from polymers adsorbed onto colloidal particles [70,71] or porous media [72] and from flat surfaces with neutron reflectivity [73] and optical reflectometry [74]. The fraction of segments bound to the solid surface is nicely revealed in NMR studies [75], infrared spectroscopy [76], and electron spin resonance [77]. An example of the concentration profile obtained by inverting neutron scattering measurements appears in Fig. XI-7, showing a typical surface volume fraction of 0.25 and layer thickness of 10-15 nm. The profile decays rapidly and monotonically but does not exhibit power-law scaling [70]. 

GATR Grazing-angle attenuated total reflecTance infrared specTroscopy... 

Infrared spectroscopy can provide a great deal of information on molecular identity and orientation at the electrode surface [51-53]. Molecular vibrational modes can also be sensitive to the presence of ionic species and variations in electrode potential [51,52]. In situ reflectance measurements in the infrared spectrum engender the same considerations of polarization and incident angles as in UV/visible reflectance. However, since water and other solvents employed in electrochemistry are strong IR absorbers, there is the additional problem of reduced throughput. This problem is alleviated with thin-layer spectroelectro-chemical cells [53]. 

Characterization. The PPNVP and PPNVP/PEUU films were characterized by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), electron spectroscopy for chemical analysis (ESCA), ellipsometry, and water contact angles in air. Two independent methods, a modification of the radioimmunoassay used by Ziats, et. al. (14) and an immunochemical stain based on the ABC immunohistochemical staining method (15) were developed to assay the binding of GOx to the PPNVP/PEUU support. 

Very thin films (monolayer or multilayer) can be studied by IR spectroscopy, provided that the IR beam crosses a reasonably large fraction of the monolayer this can be done by (i) grazing-angle techniques (whereby the IR beam angles of incidence and reflection are of the order of 1° to 3°) or (ii) multiple internal reflections of the IRbeam inside the monolayer (infrared reflectance and absorbance spectroscopy (IRRAS). Fig. 11.19 shows the chemical structure of an analyte (Fullerene-fcz s-[ethylthio-tetrakis(3,4-dibutyT2-thiophene-5-ethenyl)-5-bromo-3,4-dibutyl-2-thiophene] malonate),... 

Specular reflectance spectroscopy — Spectroscopic techniques using light in the UV-Vis and the infrared range impinging on the electrode surface and reflected away from the surface at the angle of incidence are called specular reflectance spectroscopies (see -> UV-Vis spectroscopy, -> infrared spectroscopy). 

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