Infrared spectroscopy multiple internal reflection technique

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. 

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]. 

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). 

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]. 

ATR has been found as an easy to use, non-destmctive and surface-sensitive IR sampling technique for the in situ investigation of CMP processes (Hind et al., 2001). It was initially pushed by Harrick (1967) and comprehensively treated in his early book and following editions together with Mirabella (1985). Numerous alternative and partially deceptive names are used instead of ATR spectroscopy internal reflection spectroscopy, evanescent wave spectroscopy, frustrated total internal reflection (FTIR, which should not to be confused with Fourier-transform infrared spectroscopy) and multiple internal reflection (MIR, which should not to be confused with mid-infrared )- Therefore, in the following the term ATR as defined in Section 14.4.1 and illustrated with Figure 14.8 is used exclusively. 

Internal reflection spectroscopy, also known as attenuated total reflectance (ATR) or multiple internal reflectance (MIR), is a versatile, nondestructive technique for obtaining the infrared spectrum of the surface of a material or the spectrum of materials either too thick or too strongly absorbing to be analyzed by standard transmission spectroscopy. 

Electromoduiated Infrared Spectroscopy. The form most widely in use is the electromoduiated attenuated-total-reflection-spectroscopy. This is the electromoduiated form of the multiple internal reflection spectroscopy that was previously discussed. The practice here is to modulate, by switching the potential between two values, and monitor the absorption changes by lock-in techniques. Description of this technique with an emphasis on metal-electrolyte interfaces can be found in (70). The modulation here is different from all the other techniques that were mentioned in the sense that the modulation is not a small perturbation of an equilibrium state but a shift between two equilibrium states. Whether... 

Multiple block copolymers form a domain-matrix morphology due to the chemical and steric incompatibilities of the two chemically different blocks. The surface molecular and morphological structures of a series of block copolyether-urethane-ureas have been studied in detail via Electron Spectroscopy for Chemical Analysis (ESCA) and Fourier Transform Infrared Spectroscopy (FTIR) coupled with internal reflectance techniques. ESCA provides elemental information concerning the very surface, while FTIR provides the molecular and secondary bonding Information of the surface and into the bulk. Bulk and surface chemical and morphological structures are shown to be quite different, and are affected by synthetic and fabrication variables. 

Due to the fundamental importance of the adsorbed protein film, many methods have been used to characterize its nature. These methods include ellipsometry (3,A), Fourier transform infrared spectroscopy (FTIR) (5,6), multiple attenuated internal reflection spectroscopy (MAIR) (7,8) immunological labeling techniques (9), radioisotope labeled binding studies (j ), calorimetric adsorption studies (jj ), circular dichroism spectroscopy (CDS) (12), electrophoresis (j ), electron spectroscopy for chemical analysis (ESCA) (1 ), scanning electron microscopy (SEM) (15,16,9), and transmission electron microscopy (TEM) (17-19). 

---