community user workshop on planetary libs …€¦ · introduction to libs sam clegg los alamos...
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COMMUNITY USER WORKSHOP ON PLANETARY LIBS (CHEMCAM) DATA
Introduction to LIBS
Sam Clegg
Los Alamos National Laboratory
16 Mar 2014 ChemCam Community Workshop 1
Lunar and Planetary Science Conference, March 16th, 2014
Creating LIBS Sparks
16 Mar 2014 ChemCam Community Workshop 2
Introduction to LIBS
3”
LIBS Spots and Dust Removal
16 Mar 2014 ChemCam Community Workshop 3
Introduction to LIBS
NASA/JPL-Caltech/MSSS/Honeybee Robotics/LANL/CNES
“Wernecke”
Sol 169
NASA/JPL-Caltech/LANL/IRAP/CNES/LPGNantes/IAS/CNRS/MSSS
ChemCam Dust Removal
Brushed Surface
LIBS Sensitivities, ChemCam Configuration
4
Introduction to LIBS
B** C** N** O** F Ne
Na* Mg*
Li** Be**
H** He
Al* Si* P** S** Cl** Ar
Ga Ge As** Se Br Kr
In Sn Sb Te I Xe
Tl Pb** Bi
Mn** Fe* Co Ni** Cu** Zn**
Ru Rh Pd Ag Cd**
Re Os Ir Pt Au Hg
K* Ca* Sc** Ti* V Cr**
Rb** Sr** Y Zr Nb Mo
Cs Ba** La Hf Ta W
5-100 ppm
100-1000 ppm
0.1-3%
Difficult
Approximate detection limits at Mars atmospheric pressure X* = Reported Oxides X** = To be reported
Ca LIBS Spectrum-LANL Testbed
5
Introduction to LIBS
• 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
wavelength (nm)
260 280 300 320 340
Inte
nsity
(pho
tons/D
N)
-5.0e+12
0.0
5.0e+12
1.0e+13
1.5e+13
2.0e+13
2.5e+13
wavelength (nm)
380 400 420 440 460
Inte
nsity
(pho
tons/D
N)
-5e+12
0
5e+12
1e+13
2e+13
2e+13
3e+13
3e+13
wavelength (nm)
500 550 600 650 700 750 800 850 900
Inte
nsity
(pho
tons/D
N)
-4e+12
-2e+12
0
2e+12
4e+12
6e+12
8e+12
UV Region VIS Region
VNIR Region
Ca Spectrum Neutral Ca (I) Ionized Ca (II)
Ca Spectrum Neutral Ca (I) Ionized Ca (II)
Ca Spectrum Neutral Ca (I) Ionized Ca (II) O
Raw ChemCam Spectrum – Jake_1
6
Introduction to LIBS
Peak FWHM ~3 – 4 pixels
~1.5 nm
Raw ChemCam Spectrum – Jake_1
7
Introduction to LIBS
Peak FWHM ~3 – 4 pixels
~1.5 nm
Raw ChemCam Spectrum – Jake_1
8
Introduction to LIBS
Carefully Processed Spectra Lead to Quantitative Analysis Continuum Removal, Spectral Calibration, Distance Correction are Critical
Peak FWHM ~3 – 4 pixels
~1.5 nm
ChemCam Spectra
9
Introduction to LIBS
Fully Processed Spectra Ready for Quantitative Analysis Much can be Qualitatively Observed
Chemical Matrix Effects Complicate Quantitative Analysis
10
Introduction to LIBS
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
Si (288nm)
Elemental Concentration (Atomic Fraction)
0.16 0.18 0.20 0.22 0.24 0.26
Inte
gra
ted N
orm
aliz
ed
In
ten
sity (
arb
. u
nits)
0.002
0.004
0.006
0.008
0.010
0.012
0.014
0.016
0.018
0.020
b = -9.132e-3m = 0.087r ² = 0.700
Peak Area Analysis Method
Multivariate analyses are used to compensate for these matrix effects
Quantitative Calibration
11
Introduction to LIBS
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*
* = from Dyar lab, all others from commercial sources
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
backup
12
Introduction to LIBS
Ca Electronic Energy Level Diagram
13
Introduction to LIBS
Ca Electronic Energy Level DiagramsE
lectr
onic
Ene
rgy
(cm
-1)
0
2e+4
4e+4
6e+4
8e+4
1e+5
Ca I - Neutral Atoms
Upper States
Lower States
Ca II - Ionized Atoms (1e-)
Upper States
Lower States
3 States
3 States 2 States
2 States
Emission lines are produced as atoms relax from upper state to lower state. Lower state is not always the ground state.