Infrared spectroscopy characteristic absorption patterns

In addition to the characteristic XRD patterns and photoluminescence, UV-visible and X-ray absorption spectra, another fingerprint thought to indicate lattice substitution of titanium sites was the vibrational band at 960 cm-1, which has been recorded by infrared and Raman spectroscopy (33,34). Although there is some controversy about the origin of this band, its presence is usually characteristic of a good TS-1 catalyst, although it turned out to be experimentally extremely difficult to establish quantitative correlations between the intensity of the 960 cm-1 band and the Ti content of a Ti silicate and/or its catalytic activity. 

The structures of long-chain bases can best be determined by mass spectrometry (Karlsson, 1970b). The dinitrophenylamines with their free hydroxyl groups methylated give characteristic fragmentation patterns for determination of their molecular weights and the primary structure of the base. Double-bond positions can be found if they are first hydroxylated and derivatized to TMS (tri-methylsilyl) ethers. Mass spectra can also be obtained (after GLC) of the A -acetyl, O-TMS ether derivatives of the base (Polito et aL, 1969). trans-Douhlc bonds can be identified by infrared absorption spectroscopy. 

Infrared (IR) absorption spectroscopy, especially measured by FTIR, is a powerful technique for the physical characterization of pharmaceutical solids.When the structural characteristics of a solid perturb the pattern of vibrational motion for a given molecule, these alterations can be used as a means to study the solid-state chemistry of the system. FTIR spectra often are used to evaluate the type of polymorphism that exists in a drug substance and can be very useful to study the water contained within hydrate species. Solid-state IR absorption spectra often are obtained on powdered solids through the combined use of FTIR and diffuse reflectance detection, and interpreted through conventional group frequency compilations. ... 

The remaining sections in this chapter deal with two additional methods for the determination of the structures of organic compounds infrared (IR) spectroscopy and mass spectrometry (MS). IR spectroscopy is a very useful tool because it is capable of detecting the characteristic bonds of many functional groups through their absorption of infrared light. IR spectroscopy measures the vibrational excitation of atoms around the bonds that connect them. The positions of the absorption lines associated with this excitation depend on the types of functional groups present, and the IR spectrum as a whole displays a pattern unique for each individual substance. 

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