NASA/JPL-Caltech/MSSS
Lunar and Planetary Science Conference, March
18th,
2015
COMMUNITY USER WORKSHOP
ON PLANETARY LIBS (CHEMCAM)
DATA
Introduction
to LIBS
Sam Clegg
and the ChemCam team
Creating LIBS Sparks
3”
18 Mar 2015
ChemCam Community Workshop
2
LIBS Spots and Dust Removal
ChemCam
Dust Removal
Brushed
Surface
NASA/JPLCaltech/LANL/IRAP/CNES/LPGNantes/I
AS/CNRS/MSSS
“Wernecke”
Sol 169
NASA/JPL-Caltech/MSSS/Honeybee
Robotics/LANL/CNES
16 Mar 2014
ChemCam Community Workshop
3
LIBS Sensitivies, ChemCam Configuration
Approximate detection limits
at Mars atmospheric pressure
5-100 ppm
X* = Reported Oxides
X* = Reported in literature
X* = To be reported
100-1000 ppm
H*
0.1-3%
Li* Be*
B* C* N* O* F* Ne
Difficult
Na* Mg*
Al* Si* P*
K* Ca* Sc* Ti*
Rb* Sr*
V
S* Cl* Ar
Cr* Mn* Fe* Co Ni* Cu* Zn* Ga Ge As* Se
Y
Zr
Nb Mo
Cs Ba* La
Hf
Ta
18 Mar 2015
He
W
Ru Rh Pd Ag Cd* In
Re Os
Ir
Pt
Au Hg
Sn
Sb
Te
Br
Kr
I
Xe
Tl Pb* Bi
4
Ca LIBS Spectrum-LANL Testbed
2.5e+13
1.5e+13
1.0e+13
5.0e+12
VIS Region
3e+13
Intensity (photons/DN)
Intensity (photons/DN)
2.0e+13
3e+13
UV Region
Ca Spectrum
Neutral Ca (I)
Ionized Ca (II)
2e+13
2e+13
Ca Spectrum
Neutral Ca (I)
Ionized Ca (II)
1e+13
5e+12
0.0
0
-5.0e+12
260
280
300
320
340
-5e+12
380
wavelength (nm)
Intensity (photons/DN)
440
460
• Not every NIST emission line is observed in a
LIBS spectrum.
VNIR Region
–
Ca Spectrum
Neutral Ca (I)
Ionized Ca (II)
4e+12
420
wavelength (nm)
8e+12
6e+12
400
– Every LIBS line must be found in NIST
– Typically observe neutral and first ionized atoms,
perhaps second ionization under ChemCam conditions.
O
2e+12
http://physics.nist.gov/PhysRefData/ASD/lines_form.html
• Must be Spectrally well calibrated!
0
– Know the difference between vacuum vs. air (Earth or
Mars) calibration
– Closest NIST emission line is not good enough
-2e+12
-4e+12
500
18 Mar 2015
550
600
650
700
wavelength (nm)
750
800
850
900
• More details provided in the next few
presentations
5
Raw ChemCam Spectrum – Jake_1
Peak FWHM
~3 – 4 pixels
~1.5 nm
18 Mar 2015
6
Raw ChemCam Spectrum – Jake_1
Peak FWHM
~3 – 4 pixels
~1.5 nm
18 Mar 2015
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
18 Mar 2015
8
ChemCam Spectra
Fully Processed Spectra Ready for Quantitative Analysis
Much can be Qualitatively Observed
18 Mar 2015
9
Chemical Matrix Effects Complicate Quantitative Analysis

Peak Area Analysis Method

Si (288nm)
0.020
Integrated Normalized Intensity (arb. units)
Conventional Elemental Analysis

0.018

0.016
0.014
Sample Elemental and Molecular
Composition Influences:

0.012

0.010
0.008


0.006
b = -9.132e-3
m = 0.087
r ² = 0.700
0.004
0.002
0.16
0.18
0.20
0.22
0.24
Elemental Concentration (Atomic Fraction)

Laser-to-Sample Coupling Efficiency
Chemical Reactions within the
Plasma
Collisional Quenching
Chemical Matrix Effects

0.26
Peak Area or Height vs.
Concentration
Each Peak is Analyzed
Independently
Increase Scatter and Uncertainty
Chemical Matrix Effects
Compensation


Cal-Free LIBS
Various Normalization
Multivariate analyses are used to compensate for these matrix effects
18 Mar 2015
10
Quantitative Calibration
3 m standoff distance
18 Mar 2015
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
backup
18 Mar 2015
12
Ca Electronic Energy Level Diagram
1e+5
Ca Electronic Energy Level Diagrams
Ca II - Ionized Atoms (1e )
Upper States
Ca I - Neutral Atoms
-1
Electronic Energy (cm )
8e+4
Lower States
2 States
6e+4
Upper States
4e+4
Lower States
2e+4
3 States
2 States
3 States
0
Emission lines are produced as atoms relax from upper state to lower state.
Lower state is not always the ground state.
18 Mar 2015
13