gems, gem testing, gemology, advanced gemology, advanced testing, Raman, portable Raman

While Raman spectroscopy has typically been conducted in laboratory settings, new hardware developments have made this technique available for field use. This is an important development because of the pressing need for field agents to make rapid and accurate identification of samples suspected to be dangerous. Potentially dangerous chemicals have posed a problem for most current commercial analytical instruments, particularly since some chemicals can be lethal if incorrectly handled. The Raman spectroscopy technique, however, is uniquely able to handle the analysis of dangerous chemicals because little or no sample preparation is required, it is relatively unaffected by strong infrared (IR) absorbers like water, there are no special accessories needed for aqueous solutions, and the Raman short wavelength excitation source can penetrate transparent and translucent container materials such as envelopes, plastic bags, and glass vials. The hardware developments that have enabled Raman spectroscopy to be used in field settings are described followed by a discussion of laser excitation source and wavelength choice when using Raman spectroscopy. A rugged, fiber-optic probe in portable Raman systems is a particularly important component of the mobile version, especially because of its potentially shock-sensitive compounds that would enable a scene investigator to identify potentially hazardous environments as they approach them. The data processing and system control capabilities in commercial portable Raman systems are described followed by a discussion of the applications of the portable Raman system and its practical considerations.