Absorption Spectra

Abstract

WITHOUT doubt the study of absorption spectra, more particularly those of organic compounds, has given rise to great interest, owing to the possible connection between absorption and chemical constitution. The work of Hartley, Dobbie, and others showed that in certain cases it was possible to determine the constitution of substances from observations of their absorption spectra. It is not surprising that, as the result of this work, a school of thought was founded on the basis of a direct correlation between the atomic structure of a molecule and its absorption spectrum. On the other hand, Hantzsch, who in a great number of papers has maintained the opinion that the absorption curve is an index to constitution, has travelled far beyond the original point of view. He found that changes in the absorption spectrum of a compound are observed when no change is possible in its primary valency structure, and in interpreting his results Hantzsch has invoked the aid of the secondary valencies of the atoms.