Time filter

Source Type

Fremont, CA, United States

Harmon R.S.,U.S. Army | Shughrue K.M.,Juniata College | Remus J.J.,Clarkson University | Wise M.A.,Smithsonian Institution | And 2 more authors.
Analytical and Bioanalytical Chemistry

Conflict minerals is a term applied to ores mined in conditions of armed conflict and human rights abuse. Niobium and tantalum are two rare metals whose primary natural occurrence is in the complex oxide minerals columbite and tantalite, the ore of which is commonly referred to as coltan. The illicit export of coltan ore from the Democratic Republic of the Congo is thought to be responsible for financing the ongoing civil conflicts in this region. Determining the chemical composition of an ore is one of the means of ascertaining its provenance. Laser-induced breakdown spectroscopy (LIBS) offers a means of rapidly distinguishing different geographic sources for a mineral because the LIBS plasma emission spectrum provides the complete chemical composition (i.e., "chemical fingerprint") of any material in real time. To test this idea for columbite-tantalite, three sample sets were analyzed. Partial least squares discriminant analysis (PLSDA) allows correct sample-level geographic discrimination at a success rate exceeding 90%. © 2011 Springer-Verlag (outside the USA). Source

Zorba V.,Lawrence Berkeley National Laboratory | Mao X.,Lawrence Berkeley National Laboratory | Russo R.E.,Lawrence Berkeley National Laboratory | Russo R.E.,Applied Spectra, Inc.
Analytical and Bioanalytical Chemistry

Extending spatial resolution in laser-based chemical analysis to the nanoscale becomes increasingly important as nanoscience and nanotechnology develop. Implementation of femtosecond laser pulses arises as a basic strategy for increasing resolution since it is associated with spatially localized material damage. In this work we study femtosecond laser far- and near-field processing of silicon (Si) at two distinct wavelengths (400 and 800 nm), for nanoscale chemical analysis. By tightly focusing femtosecond laser beams in the far-field, we were able to produce sub-micrometer craters. In order to further reduce the crater size, similar experiments were performed in the near-field through sub-wavelength apertures, resulting in the formation of sub-30-nm craters. Laser-induced breakdown spectroscopy (LIBS) was used for chemical analysis with a goal to identify the minimum crater size from which spectral emission could be measured. Emission from sub-micrometer craters (full width at half maximum) was possible, which are among the smallest ever reported for femtosecond LIBS. © 2009 Springer-Verlag. Source

Agency: National Aeronautics and Space Administration | Branch: | Program: SBIR | Phase: Phase II | Award Amount: 749.97K | Year: 2014

This project addresses the need for a non-contact instrument capable of measuring the isotopic ratios O-18/O-16 and D/H from water ice and other solid materials (rocks). Frozen H2O is the dominant ice in the outer solar system, recently found on the Moon. Extensive deposits of near-surface ice discovered on Mars. Oxygen and hydrogen isotopic records preserve history of water/rock interactions depending on chemistry and ambient conditions. Ratios of these isotopes are the main tool in paleoclimatology studies on Earth. A proposed non-contact optical instrument similar to ChemCam will be capable of measuring not only complete elemental compositions but also the key isotopic abundances in surface materials. We demonstrated the resolution and sensitivity required to determine these isotopes in synthetic samples and natural minerals relevant to Mars. We are utilizing and developing our recently published technology: Laser Ablation Molecular Isotopic Spectrometry (LAMIS). Our concept is simple and scientifically proven. We will advance to TRL4 with the further aim of integrating our LAMIS detector with a ChemCam-like instrument. The proposed effort leverages and advances the technology developed for ChemCam. The added strength of measuring isotopes will greatly expand the capabilities of the ChemCam, which is already a highly successful instrument onboard "Curiosity". We will develop a breadboard prototype of the instrument that can be later amended to measure other key isotopes (C, N, B, Cl, Mg, Ca, Sr). We plan further infusion in NASA missions and commercialization. The immediate focus is on Mars but our concept is also highly germane to future landing missions to the Moon, other planets and their moons, asteroids, and to a broad range of applications in ecology, agronomy, nuclear industry, radio-chemotherapy, forensics, security and other fields. Our instrument can be used for stand-alone landing missions or for in situ sample characterization prior to sample return.

Agency: National Aeronautics and Space Administration | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 100.00K | Year: 2009

This proposal addresses NASA astrobiology objectives, particularly the need for a compact instrument capable of in situ isotopic measurements. We propose the detailed conceptual development of a device for analyzing key isotopic composition in surface materials without sample preparation. We will combine absorption spectroscopy with laser induced vaporization of solid samples for high-resolution isotopic measurements. An immediate focus is on Mars but our concept is also highly germane to other applications relevant to bio- and geochemical objectives. We will evaluate accuracy, sensitivity, and resolution of our technology for isotopic detection of the key elements associated with signs of life (C, S, H, O) in solid materials. All essential design components of the proposed analyzer have been separately developed and demonstrated in very compact form for other applications. In the Phase I, we will develop technology for measuring sulfur isotope ratios in condensed samples. In the Phase II, we will demonstrate the overall performance of the proposed technique and deliver a breadboard prototype instrument. Commercial systems based on the Phase II prototype will be developed and marketed during Phase III.

A method for real-time optical diagnostics in laser ablation and laser processing of layered or structured materials or material structures. Diagnostics is provided during laser ablation that is utilized regularly in laser processing and/or chemical analysis of structured materials, by means of measuring optical emission generated as a result of the pulsed laser-material interaction in real time. The method can involve a single-layer-film or a stack of multiple layers or a structure of different domains. The method is particularly beneficial in fabrication of thin-film structures, such as photovoltaic and electronic devices or circuits of devices.

Discover hidden collaborations