There is growing interest in rapid analysis of rare earth elements (REEs) both due to the need to find new natural sources to satisfy increased demand in their use in various electronic devices, as well as the fact that they are used to estimate actinide masses for nuclear safeguards and nonproliferation. Laser-Induced Breakdown Spectroscopy (LIBS) appears to be a particularly well-suited spectroscopy-based technology to rapidly and accurately analyze the REEs in various matrices at low concentration levels (parts-per-million). Although LIBS spectra of REEs have been reported for a number of years, further work is still necessary in order to be able to quantify the concentrations of various REEs in realworld complex samples. LIBS offers advantages over conventional solution-based radiochemistry in terms of cost, analytical turnaround, waste generation, personnel dose, and contamination risk. Rare earth elements of commercial interest are found in the following three matrix groups: 1) raw ores and unrefined materials, 2) as components in refined products such as magnets, lighting phosphors, consumer electronics (which are mostly magnets and phosphors), catalysts, batteries, etc., and 3) waste/recyclable materials (aka e-waste). LIBS spectra for REEs such as Gd, Nd, and Sm found in rare earth magnets are presented.
Carbon reservoirs at the earth's surface comprise the plant and microbial, biomass, and organic and inorganic carbon in soils, lakes, rivers, and oceans. These reservoirs interact with the atmosphere and affect its CO<SUB>2</SUB> content. Soil organic carbon (SOC) is an essential constituent in all ecosystems that can be enhanced by manipulating agricultural and forest lands. A successful strategy is the determination of the amount (quantity) and the chemical composition (quality) of carbon and nitrogen stored within the soil profile. The need for rapid analysis of both the soil quantity and quality is an essential part of determining the techniques of choice for measuring SOC. We have successfully demonstrated the technique of laser-induced breakdown spectroscopy (LIBS) in the determination of the total concentration of carbon and nitrogen in soils and have also been successful in the development of electrochemical-surface enhanced Raman spectroscopy (Electro-SERS), the results for which will be reported in another article. In this article we will focus on the data obtained using the LIBS technique. Our preliminary results suggest that LIBS method can be used for developing a field deployable instrument that can be used for in situ, real time monitoring of total carbon and nitrogen in soil. We have determined the total concentration of carbon in 15 soil samples and have obtained a calibration curve for them.
A commercial FT-Raman instrument has been modified for use in on-line chemical composition analysis to control an industrial distillation column. Optical fibers are utilized to allow the placement of the instrument 35 meters from the process environment. Various process probes have been tested and compared. Computational algorithms are used to develop a mathematical model which correlates spectral characteristics to composition. Predictions from the model are presented at three minute intervals to allow statistical process control of a distillation column through operator intervention. Recent application studies and probe modifications are discussed.