Polyatomic substances groups

ABSORPTION BAND. A range of wavelengths (or frequencies) in the electromagnetic spectrum within which radiant energy is absorbed by a substance. When the absorbing substance is a polyatomic gas, an absorption band actually is composed of a group of discrete absorption lines, which appear to overlap. Each line is associated with a particular mode of vibration or rotation induced in a gas molecule by the incident radiation. The absorption bands of oxygen and ozone are often referred to in the literature of atmospheric physics. 

As a result, specific kinds of vibration modes always appear at similar frequencies for different molecules then, it is feasible to construct a table of characteristic absorption frequencies. Typical absorption band tables for significant bonds included in polyatomic molecules are reported in ref. [58], Subsequently, using the typical absorption frequencies, it is relatively simple to recognize the occurrence of functional groups in unidentified compounds, and use this information to get structural information about these substances in order to identify them. 

Epoxide resins are condensation products of substances containing the epoxy group (epichlorohydrin) with polyatomic phenols (4,4 -dihydroxy-diphenyl-2,2 -propane, resorcinol, etc.) and represent thermoplastic products with various softening points, depending on the ratio of the initial components and the conditions under which the condensation was conducted ... 

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