INFRARED SPECTROSCOPY AND POLYMORPHIC FORMS OF CRYSTALS

Author Institution: American Cyanamid Company, Calco Chemical DivisionThe application of infrared spectroscopy to the study of tautomerism, stereoisomerism, and molecular structure through the use of isotopes is well known. It has now been found that infrared techniques can be applied to the identification of polymorphic forms of both organic and inorganic crystals. Infrared spectroscopy has been conveniently and successfully used to distinguish between different crystalline forms of substances of the same chemical composition. The method complements and supplements the X-ray, microscopical, and electron diffraction techniques. The advantages and disadvantages of these various techniques for study of polymorphism will be discussed. The value of the infrared method will be illustrated by the results obtained on such pigments as the titanium dioxides, copper phthalocyanine blues, and para reds