MULTIPLE INTERNAL SPECTROSCOPY

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. 

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. 

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. 

El-Sayed, M. A. Phosphorescence-microwave multiple resonance spectroscopy. In MTP International Review of Science, Physical Chemistry Series One, Vol. 3. 

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. 

Multiple Internal Reflection Fourier Transform Infrared Spectroscopy... 

Determination of Respirable Quartz by Infrared Spectroscopy with a Multiple Internal Reflectance Accessory... 

Experimental work has shown that the analysis of quartz in respirable dust by Infrared spectroscopy using a Multiple Internal Reflectance Accessory is a viable technique that is sensitive, accurate and simple to perform. Linearity of a calibration curve from 0 to 200 micrograms has been demonstrated. A detection limit of approximately ten micrograms of quartz was obtained. An accuracy of + 35% at a 95% confidence level was demonstrated by data obtained from participation in the NIOSH PAT Program. 

Because of the dependence of the PL intensity of TiC>2 on the nature of the gas-phase molecules introduced (alcohols) and its reversibility upon elimination of the molecules by flowing dinitrogen, there is hope that such an effect can be applied to gas sensors. With the combined use of several techniques (PL, time-resolved femtosecond diffuse reflectance spectroscopy, multiple internal reflection IR absorption), the dynamics and role of photogenerated electrons and holes in the absence or presence of metals (notably platinum) are now better understood, at both the gas-solid and liquid-solid interfaces. It is also likely that not only TiOz, but other types of semiconductors will be more thoroughly investigated in the future. 

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),... 

Kolboe and Ellefsen (1962) and Michell et al. (1965) provided preliminary results indicating the feasibility of employing infrared spectroscopy to determine the lignin content of finely ground wood and pulp samples embedded in potassium chloride. Further development and refinement of this technique have led to methods for determination of lignin based on multiple internal reflectance infrared spectrometry (Marton and Sparks 1967) and diffuse reflectance Fourier transform spectrometry (Schultz et al. 1985). Lignin contents have also estimated by 13C CP/MAS/NMR spectrometry (Haw et al. 1984, Hemmingson and Newman 1985) (see Chap. 4.5). 

Ellipsometry is probably the only easy-to-use surface analysis method which can be operated in situ and in real time. On the contrary, multiple internal reflection Fourier transform infrared spectroscopy is a very powerful technique [38] but it is rather tricky to implement. Ellipsometry allows real time studies of the surface modification during exposure to the plasma, and after the treatment. Figure 10 shows for example the variation of and A ellipsometry angles upon fluorination of Si in fluorine-based plasmas as a function of pressure and gas mixture [39], thus demonstrating the sensitivity of the technique. Infrared ellipsometry has also been used with success to investigate reaction layer composition and formation on Si in CF4-based plasmas [40,41], or to monitor patterning [42]. 

IR spectroscopy is a common analytical technique in the textile industry. IR is capable of identifying fibers and their additives, as well as showing quantitative blend ratios and additive contents. The ATR (attenuated total reflection) technique, especially in its multiple form, MIR (multiple internal reflection) is of special importance in this field. The sample preparation is simple and fast the cut out swatches with appropriate surface areas are placed against each side of the MIR crystal, ensuring sufficient and uniform contact across the crystal surface. The internal reflection methods are non-destructive, so that the sample may be saved for other types of analysis, they are, further, methods of surface analysis. This is advantageous in all cases where the finish resides primarily on the fiber surface. In this case, a very strong spectrum of the finish is obtained, with minimal interference from the base fiber (Hannah et al., 1975). 

MAIR spectroscopy at IR wavelengths was used to identify the polymers, monitor any induced structural transformations after the various treatments, and verify the freedom of the thin film from residual trapped solvent or adventitious contaminants 1, 2). A model 9 internal reflection accessory (Wilks Scientific Corp.) was used in conjunction with Beckman IR-12 and IR-7 and Perkin-Elmer 21, 257, and 457 IR spectrometers to record reflection spectra of the immediate interface of the sample which was clamped against the multiple internal reflection prisms made from the thallium bromide salt KRS-5. 

Pesticides by Fmstrated Multiple Internal Reflectance Spectroscopy, Appl. Spectry. (1965) 19, 10-14... 

H. Bender, S. Verhaverheke, and M. M. Heyns, Hydrogen passivation of HF-last cleaned (100) silicon surfaces investigated hy multiple internal reflection infrared spectroscopy, J. Electrochem. Soc. 141, 3128, 1994. 

In these earlier studies, the polysaccharides were In open sample holders within the rf reactor. Thus, samples were exposed to fast moving high temperature electrons, the slower moving positive and negative ions, and free radicals as well as to uv irradiations. In all types of rf plasmas investigated, changes In surface properties of the polysaccharides were analyzed by the techniques of electron spectroscopy for chemical analyses (ESCA), electron spin resonance (ESR), multiple internal reflectance infrared spectroscopy (MIR) and chemiluminescence (CL). 

Internal reflection spectroscopy (IRS) is another promising optical detection for immunoassay [64]. Llobera et al. reported PDMS-based multiple internal reflection systems comprised of self-alignment systems, lenses, microfluidic channels, and mirrors. It is noteworthy that the LOD was lowered down to 41 nM using an air mirror [49]. 

Additional techniques exist for measuring fluid absorption at adhesive interfaces. Fourier transform infrared spectroscopy in the multiple internal reflection mode (FTIR-MIR) is an available technique for studying diffusion at the interface. FTlR-MlR has provided direct evidence of water accumulation, and therefore adhesive debonding, at the interface [12,13]. The technique of neutron reflectivity has also shown that the concentration of absorbed fluid can be significantly greater at the interface than in the bulk adhesive [14-18]. 

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