Spectroscopy in the Measurements of Acido - Basic Properties of Solids

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Abstract
In this article. applications of spectroscopic techniques shall be discussed in relation to the measurements of acido-basic properties of solid materials Solids, such as alumina [1], magnesia [2], silica alumina [3],aluminosilicates [4], and zeolitic materials with T-atoms as Ga, Ge, Si, Al, P [5], mixed oxides [6], clays and pillared clays [7], hetero-polyatomic systems having Kaggine structures [8], crystals of spinel type [9], and other super acid forming systems [10], exhibit either acidic or basic (or both) features dependent upon their constitution and nature. These solids, used as chemical accelerants (catalysts), are characterized by several of their intrinsic properties, viz., acidity, basicity, electrostatic vacancies, and surface genus [11-15]. Such properties form a very important theme in acid-base catalysis and play a very crucial role in deciding the catalytic nature of solids [16-20]. Hence, the diagnostics of such hidden domains of solids has been a subject of serious concern to spectroscopists in recent years [21-25]. Spectroscopic methods masterly applied to investigate acidities and basicities of solids reveal multitudes of information and unravel many mysteries of the nature of solid surfaces and their intrinsic and extrinsic properties [26-30]. Furthermore, the remarkable aspects of the properties of such solids, like acidity, super acidity, and basicity are that they are manifested within the system on the basis of several constraints imposed by the surface nature and type [31-33], atomic arrangements and connectivity of atoms [34] and its topology [35], electronic [36-37] and nuclear factors [38], electronegativity balance [39-40], and equilibration of atomic, bond, and average electronic polarizations of the system in question [41-42]. Hence, the magnitude-wise determination of the acidic and basic sites possessed by the solids had never been possible in a straightforward manner and with authenticity. It is, in fact, measured spectroscopically or through adsorptioddesorption process of gases/molecules on the surfaces of solids using thermal methods [43-45] or evaluated theoretically using mathematical models [46].