Experiment 14 - Infrared spectroscopy

Abstract

Infrared (IR) spectroscopy is the most extensively used method for the investigation of polymer structure and the analysis of functional groups. IR spectrometers are used to study samples in the gaseous, liquid, and solid state depending on the types of accessories used. IR is used to characterize polymer blends, dynamics, surfaces, and interfaces, as well as chromatographic effluents and degradation products. It is capable of qualitative identification of the structure of unknown materials as well as the quantitative measurement of the components in a complex mixture. Infrared radiation refers to that part of the electromagnetic radiation that is between visible and microwave regions. The infrared radiation region is divided into three regions—namely, near-infrared, mid-infrared, and far-infrared. In the near-infrared region (NIR), many absorption bands resulting from harmonic overtones and combination bands of the fundamental molecular vibrations are found. The mid-infrared region is divided into the group frequency region and fingerprint region. The far-infrared region contains the bending vibrations of carbon, nitrogen, oxygen, and fluorine with atoms heavier than mass 19 and additional bending motions in cyclic or unsaturated system.