Lunar and Planetary Science Conference, March 18 th, 2015 NASA/JPL-Caltech/MSSS COMMUNITY USER WORKSHOP ON PLANETARY LIBS (CHEMCAM) DATA Introduction to LIBS Sam Clegg and the ChemCam team
Creating LIBS Sparks 3 ChemCam Community Workshop 2
LIBS Spots and Dust Removal ChemCam Dust Removal NASA/JPL- Caltech/LANL/IRAP/CNES/LPGNantes/I AS/CNRS/MSSS Brushed Surface Wernecke Sol 169 NASA/JPL-Caltech/MSSS/Honeybee Robotics/LANL/CNES 16 Mar 2014 ChemCam Community Workshop 3
LIBS Sensitivies, ChemCam Configuration 100-1000 ppm X* = Reported Oxides H* X* = Reported in literature He X* = To be reported Li* Be* 5-100 ppm 0.1-3% Difficult Approximate detection limits at Mars atmospheric pressure B* C* N* O* F* Ne Na* Mg* Al* Si* P* S* Cl* Ar K* Ca* Sc* Ti* V Cr* Mn* Fe* Co Ni* Cu* Zn* Ga Ge As* Se Br Kr Rb* Sr* Y Zr Nb Mo Ru Rh Pd Ag Cd* In Sn Sb Te I Xe Cs Ba* La Hf Ta W Re Os Ir Pt Au Hg Tl Pb* Bi 4
Ca LIBS Spectrum-LANL Testbed 2.5e+13 2.0e+13 UV Region 3e+13 3e+13 VIS Region Intensity (photons/dn) 1.5e+13 1.0e+13 5.0e+12 Ca Spectrum Neutral Ca (I) Ionized Ca (II) Intensity (photons/dn) 2e+13 2e+13 1e+13 5e+12 Ca Spectrum Neutral Ca (I) Ionized Ca (II) 0.0 0 Intensity (photons/dn) -5.0e+12 8e+12 6e+12 4e+12 2e+12 0-2e+12-4e+12 260 280 300 320 340 VNIR Region Ca Spectrum Neutral Ca (I) Ionized Ca (II) wavelength (nm) 500 550 600 650 700 750 800 850 900 wavelength (nm) O -5e+12 380 400 420 440 460 wavelength (nm) Not every NIST emission line is observed in a LIBS spectrum. http://physics.nist.gov/physrefdata/asd/lines_form.html Every LIBS line must be found in NIST Typically observe neutral and first ionized atoms, perhaps second ionization under ChemCam conditions. Must be Spectrally well calibrated! Know the difference between vacuum vs. air (Earth or Mars) calibration Closest NIST emission line is not good enough More details provided in the next few presentations 5
Raw ChemCam Spectrum Jake_1 Peak FWHM ~3 4 pixels ~1.5 nm 6
Raw ChemCam Spectrum Jake_1 Peak FWHM ~3 4 pixels ~1.5 nm 7
Raw ChemCam Spectrum Jake_1 Peak FWHM ~3 4 pixels ~1.5 nm Carefully Processed Spectra Lead to Quantitative Analysis Continuum Removal, Spectral Calibration, Distance Correction are Critical 8
ChemCam Spectra Fully Processed Spectra Ready for Quantitative Analysis Much can be Qualitatively Observed 9
Chemical Matrix Effects Complicate Quantitative Analysis Integrated Normalized Intensity (arb. units) 0.020 0.018 0.016 0.014 0.012 0.010 0.008 0.006 Peak Area Analysis Method Si (288nm) 0.004 b = -9.132e-3 m = 0.087 r ² = 0.700 0.002 0.16 0.18 0.20 0.22 0.24 0.26 Elemental Concentration (Atomic Fraction) Conventional Elemental Analysis Peak Area or Height vs. Concentration Each Peak is Analyzed Independently Sample Elemental and Molecular Composition Influences: Laser-to-Sample Coupling Efficiency Chemical Reactions within the Plasma Collisional Quenching Chemical Matrix Effects Increase Scatter and Uncertainty Chemical Matrix Effects Compensation Cal-Free LIBS Various Normalization Multivariate analyses are used to compensate for these matrix effects 10
Quantitative Calibration 3 m standoff distance BHVO-2 DH 4912 Norite Swy-2 GBW 07105 JR-1 GYP A SGR-1 Igneous NBS688 GBW 07113 GYP C VS MO7 Sedimentary BIR-1 Ultramafic* GYP D UNS ZK Sulfur-rich BCR-2 Umph* MHC1356* GUW GNA Rover cal JA-1 Cadillac* MHC2319* M6 Haggerty* Ja2 VH-1* VZO106 GYP B Ja3 MSHA* VZO114 MHC3828* MO12 Moppin* NAu2-Hi-S UNS AK MO14 BK-2 NAu2-Med-S GBW 07313 JB-2 BWQC1* NAu2-Lo-S GBW 07316 GSR-2 Trond* KGa2-Med-S SARM51 BE-N WMG* NBS-88b STSD-1 AGV-2 VH-49* JDo-1 STSD-3 JB-3 Grano Dike* GBW 07108 STSD-4 BT-2 Macusanite NBS 97a GBW 07110 Picrite NBS 98a GBW07104 Shergottite NAu2 * = from Dyar lab, all others from commercial sources 11
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Ca Electronic Energy Level Diagram 1e+5 8e+4 Ca Electronic Energy Level Diagrams Ca II - Ionized Atoms (1e - ) Upper States Electronic Energy (cm -1 ) 6e+4 4e+4 2e+4 Ca I - Neutral Atoms Upper States Lower States 3 States 3 States 2 States 2 States Lower States 0 Emission lines are produced as atoms relax from upper state to lower state. Lower state is not always the ground state. 13