C-DEBI Research Coordination Network

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1 C-DEBI Research Coordination Network Module 3 Analyze Data Brandy M. Toner June 2012 University of Minnesota

2 C-DEBI Research Coordination Network Module 3 Analyze Data Brandy M. Toner June 2012 University of Minnesota

3 Where did the data come from? Seafloor to spectrum Buoyant plume profiling Particles on filters X-ray microprobe measurements 37 mm

4 Where did the data come from? Seafloor to spectrum z x monochromatic X-rays 1 2 sample stage 3 4 CCD camera charge coupled device X-ray diffraction (XRD) structure of all well-ordered materials Beamline Advanced Light Source Not to scale! multi-channel fluorescence detector X-ray fluorescence (XRF) (1) single location (spectrum) (2) grid of locations (map) X-ray absorption spectroscopy (XAS) (1) XANES - valence state of element of interest (2) EXAFS - local structure of element of interest

5 Where did the data come from? Seafloor to spectrum Particles on filters Areas for point measurements Single-Stage Cluster Sampling Data at Every Pixel Two-Stage Cluster Sampling 37 mm Data at Selected Particles

6 East Pacific Rise Plume Particles This iron chem map is an example of single-stage cluster sampling because spectroscopic data were collected at each pixel. The Fe XANES at specific locations, called point spectra are collected to ground truth the fit to the chem map, and are an example of two-stage cluster sampling. Fe11 Fe12 Fe3 Fe0 Fe XANES Mn XANES bkg Fe10 Fe1 Mn0 Fe8 Fe7 Mn4 Fe9 Fe2 Mn2 Fe5 Fe6 Mn3 Fe4 Fe(III)SulfideFe(II) 250 µm

7 Get SixPack, it is free Software Programs IFEFFIT (Hephaetus, Athena, Artemis, SixPack) Webb, S. M., SIXPACK: A graphical user interface for XAS analysis using IFEFFIT. Physica Scripta T115,

8 Database Independent Analysis Principal Component Analysis 13 spectra 5 components

9 Spectral Database Evaluation Target Transformation Analysis Pyrite is an excellent match for this dataset

10 Learn More about PCA Malinowski, E. R., Determination of the number of factors and the experimental error in a data matrix. Anal. Chem. 49, Malinowski, E. R., Theory of error for target factor analysis with applications to mass spectrometry and nuclear magnetic resonance spectrometry. Anal. Chim. Acta 103, Ressler, T., Wong, J., Roos, J., and Smith, I. L., Quantitative speciation of Mnbearing particulates emitted from autos burning (methylcyclopentadienyl)manganese tricarbonyl-added gasolines using XANES spectroscopy. Environmental Science and Technology 34, Manceau, A., Marcus, M. A., and Tamura, N., Quantitative speciation of heavy metals in soils and sediments by synchrotron x-ray techniques. In: Fenter, P. A., Rivers, M. L., Sturchio, N. C., and Sutton, S. R. Eds.), Applications of synchrotron radiation in lowtemperature geochemistry and environmental science. Mineralogical Society of America, Washington D.C.

11 EXAFS Linear Least-Squares Fit, Combinations chem map error estimator They are free! Software Programs Marcus, M. A., MacDowell, A., Celestre, R., Manceau, A., Miller, T., Padmore, H. A., and Sublett, R. E., Beamline at ALS: a hard X-ray microprobe for environmental and material sciences. J. Synchrotron Rad. 11,

12 Iron XANES Spectroscopy Two-Stage Sampling Speciation of Particulate Iron This is an example of a point spectrum (white squares are data) Point Spectrum at Spot 1 Normalized Absorbance EPR_L1_R2_10_FeXANES_001.e Energy (ev) X-ray Absorption Near Edge Structure (XANES) Spectroscopy 736

13 Point Spectrum at Spot 1 Normalized Absorbance line ferrihydrite 0.16 Goethite NNS 6.9E-5 Database Dependent Analysis Linear Combination Fitting Fe(III) oxyhydroxides are supported by the fit 0.1 EPR_L1_R2_10_FeXANES_001.e Energy (ev) 736 Residual = difference between fit and data Fit = linear combination of reference spectra; linear least squares fitting Data (white squares) = normalized point spectrum

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15 Iron Chemical Mapping Single Stage Sampling Iron Speciation at Every Pixel

16 Iron Chemical Mapping Single Stage Sampling Iron Speciation at Every Pixel

17 Iron Chemical Mapping Single Stage Sampling Calculate Mole Fraction of Iron Species Toner et al Oceanography

18 Iron Chemical Mapping Single Stage Sampling Estimating Error

19 Measurement & Analysis Cycle Repeats for Each Element of Interest Elemental Distribution XRF Validate Chem Map Speciation Assessment point spectra Quantify Species chem map Build Database Principal Component Analysis Target Transformation Analysis Linear Combination Fitting Choose Incident Energies Estimate Error