Raman Spectroscopy in Process AnalysisUpdate based on the original article by M. Anne Leugers and Elmer D. Lipp, Encyclopedia of Analytical Chemistry , © 2000, John Wiley & Sons, Ltd.

Abstract

Process analysis involves the on‐line measurement of chemical or physical properties of a process, generally a manufacturing process, which provides timely data so that the process can be monitored and conditions adjusted if necessary. As a tool for process analysis, Raman spectroscopy has some desirable attributes. Foremost among these are the options for sampling. The use of visible and near‐infrared (NIR) light for the Raman measurement allows the use of commonly available fiber optics for both delivery of light to a sampling point, and then collection of the scattered light and return to a spectrometer. The probes can be insertable into a process or fully noncontact. The noncontact probes operate through windows on the process and provide one of the few means of collecting analytical information without disturbing the process. Raman spectra often provide a high level of chemical and structural information, and the seconds to minutes time frame of the measurement is well suited to process control. In this article, we discuss modern Raman instrumentation and provide a number of application examples, both conventional manufacturing processes and unconventional applications, where the principles and goals of process analysis still apply.