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dc.contributor.authorMichel, Anna Pauline Miranda
dc.date.accessioned2008-01-07T20:22:10Z
dc.date.available2008-01-07T20:22:10Z
dc.date.issued2007-09
dc.identifier.urihttp://hdl.handle.net/1912/1957
dc.descriptionSubmitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution September 2007en
dc.description.abstractPresent-day expeditionary oceanography is beginning to shift from a focus on short- term ship and submersible deployments to an ocean observatory mode where long- term temporally-focused studies are feasible. As a result, a critical need for in situ chemical sensors is evolving. New sensors take a significant amount of time to develop; thus, the evaluation of techniques in the laboratory for use in the ocean environment is becoming increasingly important. Laser-induced breakdown spectroscopy (LIBS) possesses many of the characteristics required for such in situ chemical sensing, and is a promising technique for field measurements in extreme environments. Although many LIBS researchers have focused their work on liquid jets or surfaces, little at- tention has been paid to bulk liquid analysis, and especially to the effect of oceanic pressures on LIBS signals. In this work, laboratory experiments validate the LIBS technique in a simulated deep ocean environment to pressures up to 2.76 × 107 Pa. A key focus of this work is the validation that select elements important for understand- ing hydrothermal vent fluid chemistry (Na, Ca, Mn, Mg, K, and Li) are detectable using LIBS. A data processing scheme that accurately deals with the extreme nature of laser-induced plasma formation was developed that allows for statistically accu- rate comparisons of spectra. The use of both single and double pulse LIBS for high pressure bulk aqueous solutions is explored and the system parameters needed for the detection of the key analytes are optimized. Using both single and double pulse LIBS, the limits of detection were found to be higher than expected as a result of the spectrometer used in this experimentation. However, the results of this validation show that LIBS possesses the characteristics to be a viable chemical sensing method for in situ analyte detection in high pressure environments like the deep ocean.en
dc.description.sponsorshipNational Science Foundation for support of this research under grants OCE0352278 and OCE0352242. Additional support was received from WHOI’s Deep Ocean Exploration Institute who awarded this research with two grants. The WHOI Ocean Ventures Fund and the Department of Defenseen
dc.format.mimetypeapplication/pdf
dc.language.isoen_USen
dc.publisherMassachusetts Institute of Technology and Woods Hole Oceanographic Institutionen
dc.relation.ispartofseriesWHOI Thesesen
dc.subjectChemical detectorsen_US
dc.subjectHydrographyen_US
dc.titleLaboratory evaluation of laser-induced breakdown spectroscopy (LIBS) as a new in situ chemical sensing technique for the deep oceanen
dc.typeThesisen
dc.identifier.doi10.1575/1912/1957


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