The Absorption and Reflection Character of Infrared Bands of Powdered Inorganic Materials

摘要

The report approaches the problem of inconsistencies in the infrared spectra of powdered inorganic materials from the standpoint of optical physics. It shows that reflection losses predominate in the KBr pellet spectra of such materials and that many of the bands do not have the absorption character ordinarily associated with organic infrared spectra. The report reviews the underlying optical principles, compares the single crystal reflection spectra with the powder transmission spectra of 14 various oxides and fluorides of both lattice and molecular crystals and, by use of the oscillator parameters derived from dispersion analysis, develops a set of rules for interpreting powder spectra bands in terms of their absorption or reflection character. The primary conclusions of the report are that powder spectra have their greatest value for materials identification by spectrum matching, and that gross errors can arise from overusing these spectra by making vibrational assignments at each of the transmission minima. (Author)