Infrared spectroscopy history

The Adoption of Infrared Spectroscopy by Chemists," Isis 78 (1987) 3154 and S. Nunziante Cesaro and E. Torracca, "Early Applications of Infra-Red Spectroscopy to Chemistry," Ambix 35 (1988) 3947. On LeComte, Cabannes, and Langevin, see Gueron and Magat, "A History," 78 also see Jean Cabannes,... 

The following chapters describe the most important work in the different fields. Comprehensive reviews of the history of vibrational spectroscopy have been published by Jones (1981, 1985). Mbller and Rothschild (1971) have compiled a complete bibliography of far-infrared spectroscopy covering the period between 1892 and 1969. Reviews of the history of the Raman effect have been published by Brandmiiller and Kiefer (1978) and by Long (1988). 

Quite early in the history of infrared spectroscopy, reflections in form of reststrahlen bands were observed indicating strong absorption. Nowadays infrared spectroscopy is widely applied to organic compounds which are comparably weak absorbers. For their studies such reflection methods are favoured, whose results are interpretable in almost the same way as transmittance spectra are. However, there is an increasing interest in applying other reflection techniques also to such samples. Advantageous aspects are ... 

Tt is well-known that Werner determined the structure of a number of metal complexes by skillfully combining his famous coordination theory with chemical methods (30). Modern physico-chemical methods such as x-ray diffraction and infrared spectroscopy, used in the study of Werner complexes, have paralleled the development of these techniques. The results of these investigations have not only confirmed the validity of Werner s coordination theory but have also provided more detailed structural and bonding information. In early 1932, Damaschun (13) measured the Raman spectra of seven complex ions, such as [Cu(NH3)4]" and [Zn(CN)4j and these may be the first vibrational spectra ever obtained for Werner complexes. In these early days, vibrational spectra were mainly observed as Raman spectra because they were technically much easier to obtain than infrared spectra. In 1939, Wilson 35, 36) developed a new theory, the GF method," which enabled him to analyze the normal vibrations of complex molecules. This theoretical revolution, coupled with rapid developments of commercial infrared and Raman instruments after World War II, ushered in the most fruitful period in the history of vibrational studies of inorganic and coordination compounds. 

Copolymer Analysis. Even though the overall copolymer composition can be determined by residual monomer analysis, it still is necessary to have reliable quantitative techniques for copolymer composition measurements on the actual copolymer, mainly because concentration detectors for SEC or HPLC are sensitive to composition and because the conversion histories are not always available. Some of the techniques used to determine copolymer composition are melt viscometry (46), chemical analysis, elemental analysis, infrared spectroscopy (IR), Nuclear Magnetic Resonance (NMR), ultra-violet spectroscopy (UV), etc. Melt viscometry, chemical and elemental analysis are general techniques that can be applied to almost any polymer. The spectroscopic techniques can be applied depending on the ability of the functional groups present to absorb at specific wavelengths. 

Available analytical performance data for fecal fat measurements in the UK also indicate that the test should now be consigned to history. Eighty-two per cent of laboratories use no internal quality control and EQA is impractical. When the titration step was assessed in an EQA exercise, between-laboratory coefficients of variation for three samples ranged from 31% to 42%. Infrared spectroscopy offers the possibility of improved within- and between-laboratory precision for fecal fat measurements, but does not address the problems of dietary input and sample collection, and is unlilcely to be available to most laboratories. 

A. Lee Smith,. Applied Infrared Spectroscopy Fundamentals, Techniques, and Analytical Problem-Solving. New York Wiley, 1979. Comprehensive treatment of IR spectroscopy. Includes history, instrumentation, sampling techniques, qualitative and quantitative applications. 

Most of the development work on molecular markers (MMs) has resulted from the use of GC-MS, but with advances in other techniques it is clear that this field will benefit from making greater use of alternative identification methods, such as Fourier transform infrared spectroscopy and nuclear magnetic resonance techniques. Isotopic measurements can now be used to obtain complimentary information on the history and origin of a sample. It is now possible to perform a forensic investigation using stable carbon isotopic analyses on individual MMs by GC-Isotope Ratio MS without prior isolation of com-... 

The detection of short-lived transient species is often achieved by flash photolysis where an extremely short flash of UV/Vis radiation from a laser generates a high concentration of transient species, and a second probe beam monitors any changes that occur after the flash. Traditionally, UVA is spectroscopy has been used as a detection method. However, time-resolved infrared spectroscopy (TRIR), a combination of UV flash photolysis and fast IR detection, also has a long history. There are several different approaches to fast IR spectroscopy and the method of choice depends upon the timescale of the reaction. Measurements on the nanosecond to millisecond timescale are obtained using point-by-point techniques or by step-scan FTIR. In the point-by-point approach, a continuous wave IR laser (GO or diode) or globar is used as the IR source, which is tuned to one particular IR frequency (Figure 3). ... 

Infrared spectroscopy is also frequently used in the quantitative determination of the proportion of diads. As a rule, the assignment of the different diad signals is made possible from results with polymers or oligomers of known configuration. In certain cases, the calculation of the absorption frequency for the individual types has already been performed. The CH and CH2 deformational vibrations refer directly to various configurations. Since products of different stereoregularity crystallize to different extents, and since IR spectra are sensitive to crystallinity in the range 670-1000 cm then the diad content can also be determined by means of what are called crystallinity bands. However, the method is often unsuitable, since the crystallinity of the polymer depends on its previous thermal history (Chapter 5). 

Infrared spectroscopy (IR), differential scanning calorimetry (DSC) and soluble fractions are indirect methods to estimate the stereoregularity of the sample as they are related to its crystallinity and, therefore, are dependent on its thermal history. 

W. G. Wearmouth, Infrared Spectroscopy, Lab. Practice 2, 297-300, 373-376, 422-427,1953. A review of the history, basic principles, and theories of infrared spectroscopy, and of instruments used. 19 references. 

Infrared spectroscopy has a long history, which is briefly described in Chapter 1. Its measurement methods have experienced great changes over the past several decades, and improvements of the methods are still occurring. Lasers, not only as sources of infrared radiation but also as elements for nonlinear spectroscopy such as sum-frequency generation... 

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