Multiple Internal Reflectance

The above discussion was based on the premise of a single internal reflection. An increase in sensitivity can be realized through the use of multiple internal reflections. In the case of multiple reflections, the absorbance A becomes... 

Latexes of synthetic resins are identified by ir spectrometry. Selective extraction with organic solvents is used to obtain purified fractions of the polymers for spectrometric identification. Polymeric films can be identified by the multiple internal reflectance ir technique, if the film is smooth enough to permit intimate contact with the reflectance plate. TAPPI and ASTM procedures have not been written for these instmmental methods, because the interpretation of spectra is not amenable to standardization. 

Multiple internal reflection IR spectra (ATR- IR) to measure e.g. the relative absorption of C00H, NH2 and CH2 bands at 1730,... 

Figure 3.1. Showing geometries for (a) RAIRS (IRAS), where 80° < 0 < 89° and (b) Multiple Internal Reflection spectroscopy (MIR), where 0 > 0criticai-...

Multiple Internal Reflection Spectroscopy (MIR) is an alternative approach in which the IR beam is passed through a thin, IR transmitting sample such that it undergoes total internal reflection alternately from the front and rear faces of the sample (Figure 3.1(b)). At each reflection, some of the IT radiation may be absorbed by species adsorbed on the solid surface. 

Multiple internal reflectance No test Same as USP std.LDPE or HDPE Same as USP std. of PET or PETG... 

The methods of choice for the determination of acrylonitrile in environmental samples are GC/NPD (Page 1985), GC/FID (EPA 1982a), and GC/MS (EPA 1982b). Multiple internal reflectance infrared spectrometry (Jacobs and Syrjala 1978) is useful for monitoring low levels of acrylonitrile in air. 

We wondered why NSCs proliferated exclusively on surfaces with EGF-His ligands anchored by coordination. We focused on two aspects in particular the conformational integrity of coordinated EGF-His and the stability of coordinate bonds at the interface. Conformational information was acquired with multiple internal reflection-infrared absorption spectroscopy (MIR-IRAS) [97]. The stability of coordinate bonds was assessed by culturing NSCs on a surface with a small region of EGF-His ligands anchored by coordination. This spatially restricted EGF-His anchoring enabled an intuitive exploration of EGF-His release under cell culture conditions. 

Fig. 12. Transmittance of a Si multiple internal reflection plate before and after H-implantation at room temperature. [From Stein (1975). Reprinted with permission from Journal of Electronic Materials, Vol. 4, p. 159 (1975), a publication of The Metallurgical Society, Warrendale, Pennsylvania.]...

N. J. Harrick and G. I. Loeb, Multiple internal reflection spectrometry, Anal, Chem, 45, 687-691 (1973). 

Schulten, H.-R., and Soldati, F. (1981). Identification of ginsenosides from Panax ginseng in fractions obtained by high-performance liquid chromatography by field desorption mass spectrometry, multiple internal reflection infrared spectroscopy and thin layer chromatography. J. Chromatogr. 212, 37-i9. 

Solid state spectra can be measured by the Attenuated Total Reflectance or Multiple Internal Reflection methods as well as by simple transmission techniques (222). Brooker (223) has reported the discovery of the translational vibrations of NaN02, NaNOs, and CaCOs (calcite). The orientation of the bonds in (U02)(N0s)2. 6 H2O has been ascertained from the spectra obtained in this manner (223). 

The most commonly used technique for obtaining a spectrum is the attenuated total reflectance (ATR) method in the multiple internal reflectance (MIR) mode. In this method, the infrared beam is passed into a special crystal of a selenide (KRS-5). The angle of incidence is such that the beam will bounce along the crystal. A sample of the polyurethane is placed hard up against the crystal. The infrared just penetrates into the material before it continues down the crystal. A number of internal bounces are obtained along the crystal. Up to 25 reflectances are obtained from a 2 mm crystal. Figure 9.8 illustrates the infrared path in an ATR cell. 

Jackman, R.J., Queeney, K.T., Herzig-Marx, R., Schmidt, M.A., Jensen, K.F., Integration of multiple internal reflection (MIR) infrared spectroscopy with silicon-based chemical microreactors. Micro Total Analysis Systems, Proceedings 5th Y7AS Symposium, Monterey, CA, Oct. 21-25, 2001, 345-346. 

Diffuse Reflectance, Attenuated Total Reflection or Multiple Internal Reflection, Photoacoustic (PAS), Photothemal Beam Deflection, Specular Reflection Absorption, and forensic applications with the diamond cell and the Fourier transform infrared (FTIR) microscope. In museum laboratories, FTIR applications have been used for problems of identification and degradation in art and archeology. (14)... 

Multiple Internal Reflection Fourier Transform Infrared Spectroscopy... 

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