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Determining the Valence State of Lead in Compounds Using PIXE

Determining the Valence State of Lead in Compounds Using PIXE. Andrew Voter Nuclear group July 23, 2007. Motivation. Valence state is the charge on the metal ion Why is it important to know this? - Synthesis of new compounds leads to new questions about chemical structure and function.

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Determining the Valence State of Lead in Compounds Using PIXE

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  1. Determining the Valence State of Lead in Compounds Using PIXE Andrew Voter Nuclear group July 23, 2007

  2. Motivation • Valence state is the charge on the metal ion • Why is it important to know this? - Synthesis of new compounds leads to new questions about chemical structure and function

  3. Hope Ion Beam Analysis Lab (HIBAL) • Accelerates ions through a large potential to high energies • Can accelerate protons or alpha particles • We observe what happens after the ions hit the target

  4. Particle Induced X-ray Emission (PIXE) • Accelerated protons excite inner electron shells of the target • Other electrons fill the gap and give off large amounts of energy in the form of X-rays • These X-rays are detected; their energy identifies the elemental source, and the number of x-rays identifies concentration

  5. L La peak Lβ peak The Goal A Typical Lead PIXE Spectra • “Influence of chemical environment on the analysis of PIXE/XRF spectra of samples containing various compounds”1 • i.e. peaks change (slightly) Energy 1Fazinic, S. et al.; XI Intl. Conf. on PIXE. May25-29, 2007.

  6. What causes this change? • Valence state of element in compound • Crystal structure of the compound • Cell parameters of the compound • Statistics • Something else…

  7. Preparation of Samples • Compound mixed with organic binder • Pellet pressing with hydraulic press • Pellet is then mounted onto a slide • Slide placed in PIXE chamber

  8. The Procedure • Tested Cu, Mn, Pb compounds • Compounds appear sorted by valence state Pb (0) metal PbO2 (IV) • Size effect too? Energy

  9. Future Work • Double blind test of unknown element • Testing compounds of more elements (more Mn, Cr, Ru?) • Publish results

  10. Acknowledgements • Dr. Graham Peaslee • Dr. Paul DeYoung • Dave Daugherty • Nuclear Group • R.E.A.C.H. Program • Hope College • NSF

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