Raman spectroscopy for process/quality control

Analytical instrumentation, especially Near Infrared (NIR), and Gas Chromatography (GC) has been applied for a considerable number of years to the monitor and control of chemical manufacturing processes. By measuring the chemical species at the time and place of manufacture it becomes possible to modify the quantities of feedstock and the physical conditions, either manually or automatically, in order to improve the efficiency of the process and/or the quality of the product. While the information content of Raman spectra was always attractive for this type of application, implementation of Raman instrumentation was impractical until the last several years. The evolution of Raman instrumentation in the last 5 years, as well as the implementation of the mathematical data treatments that provide the needed quantitative information will be reviewed. Applications that are in the public domain will be described. This includes monitoring quality of hard carbon coatings on computer hard discs, chemical composition (mixtures, solvent separations, reactions such as polymerization, hydrogenation and curing etc.), gas composition, fermentation, polymorphy in pharmaceuticals, and polymer morphology. Rather than attempting to be exhaustive, the topics and literature covered will be selective - we will attempt to describe the state-of-the-art of a rapidly developing field, and give a sense of its potential.