Fourier transform infrared optical system

Miniaturized chemical analysis systems have been developed for most macroscopic counterparts (Dittrich et al. 2006). The availability of optical fibers, light sources, and detectors in the visible UV and near-infrared (NIR) wavelengths makes it possible to integrate spectroscopic measurements in microreactors (Lobbecke et al. 2005). Fourier transform infrared spectroscopy (FTIR) is an efficient, broadly applicable... 

All infrared spectra were recorded with an IR-PLAN microscope (IR-PLAN is a registered trade mark of Spectra Tech, Inc.) integrated to a Perkin-Elmer Model 1800 Fourier transform infrared (FT-IR) spectrophotometer. The spectrophotometer consisted of a proprietary heated wire source operated at 1050°C, a germanium overcoated potassium bromide beamsplitter, and a narrow-band mercury-cadmium-telluride (HgCdTe) detector. The detector was dedicated to the microscope and had an active area of 250 x 250 pm. The entire optical path of the system microscope was purged with dry nitrogen. 

Modern NIR equipment is generally robust and precise and can be operated easily by unskilled personnel [51]. Commercial instruments which have been used for bioprocess analyses include the Nicolet 740 Fourier transform infrared spectrometer [52, 53] and NIRSystems, Inc. Biotech System [54, 55]. Off-line bioprocess analysis most often involves manually placing the sample in a cuvette with optical pathlengths of 0.5 mm to 2.0 mm, although automatic sampling and transport to the spectrometer by means of tubing pump has been used (Yano and Harata, 1994). A number of different spectral acquisition methods have been successfully applied, including reflectance [55], absorbance [56], and diffuse transmittance [51]. 

The use of infrared spectroscopy in the Earth and environmental sciences has been widespread for decades however, until development of the attenuated total reflectance (ATR) technique, the primary use was ex situ material characterization (Chen and Gardella, 1998 Tejedor-Tejedor et al., 1998 Degenhardt and McQuillan, 1999 Peak et al., 1999 Wijnja and Schulthess, 1999 Aral and Sparks, 2001 Kirwan et al., 2003). For the study of environmental systems, the strength of the ATR-Fourier transform infrared (FTIR) technique lies in its intrinsic surface sensitivity. Spectra are collected only from absorptions of an evanescent wave with a maximum penetration depth of several micrometers from the internal reflection element into the solution phase (Harrick, 1967). This short optical path length allows one to overcome any absorption due to an aqueous phase associated with the sample while maintaining a high sensitivity to species at the mineral-water interface (McQuillan, 2001). Therefore, ATR—FTIR represents a technique capable of performing in situ spectroscopic studies in real time. 

Optical remote sensing (ORS) technologies, employing infrared spectral analysis techniques, have been utilized in the development of chemical agent standoff detection technologies. Within the ORS technologies, there are two types of remote sensing systems passive and active (laser). The section below only looks at the passive system, which employs a Fourier Transform Infrared (FTIR) spectrometer. 

The use of cylindrical internal reflectance cells for HP-IR was pioneered by Moser and further modified by others.This method involves the use of an optically transparent internal reflectance crystal (typically ZnS, ZnSe, sapphire). Due to the inherently short path length, the method is not as sensitive as transmission-based IR, and a Fourier transform infrared (FTIR) spectrometer is therefore generally required. In addition, the type of crystal may need to be changed depending on the reaction of interest, as the optics may be corroded by some reagents or catalysts. However, as the path length is fixed regardless of conditions, it is much easier to quantify catalyst species, and unlike transmission systems the cells can also be used for the study of liquid-solid and gas-liquid-solid mixtures. ... 

Lendl B, Schindler R, Frank J, Kellner R, Drott J, Laurell T (1997) Fourier transform infrared detection in miniaturized total analysis systems for sucrose analysis. Anal Chem 69 2877-2881 Lenshof A, Ahmad-Tajudin A, Jaras K, Sward-Nilsson AM, Aberg L, Marko-Varga G, Malm J, Lilja H, Laurell T (2009) Acoustic whole blood plasmapheresis chip for prostate specific antigen microarray diagnostics. Anal Chem 81 6030-6037 Lin VSY, Motesharei K, Dancil KPS, Sailor MJ, Ghadiri MR (1997) A porous silicon-based optical interferometric biosensor. Science 278 840-843... 

FrumarovS B., Nemec P., Frumar M., Oswald J., Vlcek M. Synthesis and optical properties of Ge-Sb-S PrCU system glasses. J. Non-Cryst. Solids 1999 256 2S7 266 Galeener F.L., Leadbetter A.J., Stringfellow M.W. Comparison ofthe neutron, Raman, and infrared vibrational-spectra ofvitreous Si02, Ge02, and BeFa- Phys. Rev. B 1983 27 1052 Griffiths P.R., de Haseth J.A. Fourier Transform Infrared Spectrometry, New York John Wiley Sons, 1986, Chapter 10... 

Uemura T., Nishida K., Sakakida M., Ichinose K., Shimoda S., and Shichiri M., Non-invasive blood glucose measurement by Fourier transform infrared spectroscopic analysis through the mucous membrane of the lip Application of a chalcogenide optical fiber system. Front. Med. Biol Eng., 9,137-153(1999). 

The conventional spectrometer with a dispersive prism or grating has been largely superseded by the Fourier transform infrared (FTIR) technique. This uses a moving mirror in an interferometer to produce an optical transform of the infrared signal. Numerical Fourier analysis gives the relation of intensity and frequency, that is, the IR spectrum. The FTIR technique can be used to analyze gases, liquids, and sohds with minimal preparation in short times. The FTIR technique has been applied to the study of many systems, including adsorption on polymer surfaces, chemical modification, and irradiation of polymers and oxidation of rubbers [66]. The application of infrared spectroscopy to the study of polymers has been reviewed by Bower and Maddams [62]. 

Starch and its blends have attracted much attention as environmentally biodegradable polymers (29-31). However they suffer fi-om disadvantages as compared with conventional polymers and blends such as brittleness and a narrow processability window (32). The thermal behavior and phase morphology of starch-blend systems have been studied by differential scanning calorimetry (DSC), Fourier Transform Infrared (FTIR) spectroscopy, scanning electron microscopy solvent extraction. X-ray diffraction, optical rotation, nuclear magnetic resonance (NMR) and polarizing optical microscopy (33-36). Like polymer blends wide applications starch-based blends have the potential to be... 

A rheoopticai method includes a mechanical test under static conditions (tensile test, stress relaxation, cyclic test) carried out simultaneously with an optical measurement. Among other optical methods such as x-ray scattering, nmr spectroscopy, polarized fluorescence or birefringence, the Fourier transform infrared (flir) spectroscopy has become one of the most frequently applied tools in rheooptics (22). Advantage of infrared spectroscopy is its sensitivity, rapidity, and the ability to investigate changes of molecular orientations not only in separate structural units but also in various phases of multiphase systems. From the ratio of intensities of beams polarized parallel and perpendicular to the deformation direction, orientation functions can be calculated. 

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