Collaborative Research: Oceanic Applications of Laser Induced Breakdown Spectroscopy: Laboratory Validation

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Project SummaryP.I. Chave, Alan (WHOI) Proposal #: 0527927P.I. Angel, Stanley (South Carolina) Proposal #: 0527910PROJECT TITLE: Oceanic Applications of Laser Induced Breakdown Spectroscopy: Laboratory ValidationProject SummaryThe goal of the proposed work is to investigate, characterize, and quantify a LIBS system in the laboratory for bulk aqueous solutions typical of the oceans at high pressure with some emphasis being placed on future applications at hydrothermal vent systems at mid-ocean ridges. The major products of the proposed work will be important instrumental parameters, in situ calibration standards, and fundamental, new information about LIBS plasmas at high pressure. This work will be critical to the future development of LIBS systems for in situ oceanic applications. The development of in situ chemical and biological sensors is a high priority in the ocean sciences, as is recognized in the reports from recent ocean sciences workshops. In particular, a realtime, non-invasive, multi-element chemical sensing capability which does not require sample preparation would be a significant advance over current oceanographic technology. The proposed work will support essential laboratory investigations required to implement such a sensor. Over the past two decades, a new spectroscopic technique called laser induced breakdown spectroscopy (LIBS) has been developed and is rapidly gaining favor for in situ field measurements in hostile environments. The LIBS technique utilizes a high power laser focused on a sample to create a plasma or "laser spark". A gated spectrometer covering part or all of the ultraviolet through near infrared range is used to capture the plasma spectrum. The plasma radiates both a continuum component which decays relatively rapidly and an emission line component which decays more slowly. The spectral line wavelengths and intensities obtained from plasma ablation can be compared with a standard atomic line reference and/or calibrated against samples of known makeup to determine the chemical composition of the sample. This relatively simple apparatus yields simultaneous sensitivity to virtually all elements in the parts-per-million or better range in solids, liquids, gases and aerosols. The approach is effectively non-invasive due to very small sampling regions and requires no sample preparation. It is also fast and is essentially a real-time measurement.