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Scattering Techniques

Scattering Techniques. Lecture 17 G.J. Mankey gmankey@mint.ua.edu. Elastic-no energy loss. Light Reflectometry Ellipsometry* X-rays Diffraction* Reflectometry Electrons Diffraction* Neutrons Diffraction Small Angle Neutron Scattering* Reflectometry*.

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Scattering Techniques

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  1. Scattering Techniques Lecture 17 G.J. Mankey gmankey@mint.ua.edu

  2. Elastic-no energy loss. Light Reflectometry Ellipsometry* X-rays Diffraction* Reflectometry Electrons Diffraction* Neutrons Diffraction Small Angle Neutron Scattering* Reflectometry* Inelastic-energy loss to excitation. Light Raman* Brillouin* X-rays EXAFS* Electrons HREELS* Ion Scattering* Neutrons Inelastic Neutron Scattering Scattering

  3. Inelastic Light Scattering • Brilloin Scattering-Scattering from an acoustic phonon. • Raman Scattering-Scattering from an optical phonon.

  4. EXAFS • Fine structure in the vicinity of the adsorption edges contains information about the local environment of the chemical species. ref: Prof. Brian Tonner, UCF

  5. X-Ray Absorption • Photon energy is tuned to elemental core level. • Technique probes chemical composition. • Requires a synchrotron x-ray source and monochromator. ref: Prof. Brian Tonner, UCF

  6. X-Ray Adsorption Measurements • Each method of measurement has advantages specific to the detection method. ref: Prof. Brian Tonner, UCF

  7. The electron probing depth follows the "Universal Curve." This is also true for electron spectroscopies. The curve has the form: Where A and B are material dependent parameters. To first approximation, A and B are the same for all metals. Electron Inelastic Mean Free Path ref: Prof. Brian Tonner, UCF

  8. Information in XAS • The range of energy losses probed give different information about the local environment of the chemical species with the particular adsorption edge. ref: Prof. Brian Tonner, UCF

  9. HREELS Ref: http://nano.kaist.ac.kr/2002ch607/Ch5-VIb.pdf

  10. Electron Scattering Mechanism Ref: http://nano.kaist.ac.kr/2002ch607/Ch5-VIb.pdf

  11. HREELS Example Ref: http://nano.kaist.ac.kr/2002ch607/Ch5-VIb.pdf

  12. Ion Scattering Spectroscopy Ref: http://nano.kaist.ac.kr/2002ch607/Ch5-VIb.pdf

  13. Properties of Neutrons ref: SNS Website

  14. Neutron Scattering ref: T.E. Mason

  15. Reciprocal Space ref: T.E. Mason

  16. Small Angle Neutron Scattering • Neutrons probe length scales comparable to TEM and soft x-rays. • Neutrons are a gentle probe since their energies are of the order of a few milli electron volts as opposed to hundreds to thousands of electron volts for x-rays and electrons. ref: Charles Glinka, NIST

  17. Contrast • The contrast mechanism for neutrons scattering length density rather than electron density for x-rays. ref: T.E. Mason

  18. SANS Instrumentation • Nanoscale lengths are probed. ref: Charles Glinka, NIST

  19. Neutrons Probe Magnetic Structure • The magnetic scattering length in Fe is 1/3 of the chemical scattering length, so SANS also probes magnetic structures. ref: Charles Glinka, NIST

  20. Neutron Reflectometry • Q-dependent reflectivity gives interfacial roughness and correlation length. • Polarized reflectometry yields magnetic roughness. ref: T.E. Mason

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