Multivariate Analysis of LIBS Spectra for Geomaterial Identification, Discrimination, and Classification
A commercial 'close-in' benchtop LIBS system with broadband detection from ~200-965nm and a developmental 25m 'stand-off' LIBS system with broadband detection from ~200-840nm were used to acquire single-shot LIBS spectra for a wide variety of carbonate and silicate minerals, rocks, and soils. Classification has been achieved with a high degree of success using two different chemometric techniques,soft independent method of class analogy' (SIMCA) and partial least squares discriminant analysis' (PLS-DA). By using multivariate chemometric techniques, even chemically similar geological materials can be readily discriminated. Because each broadband LIBS spectrum records the complete elemental character of the sample analyzed and therefore can be considered a unique 'geochemical fingerprint', it is possible to discriminate different samples of the same mineral, rock, or soil type.