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Scattering Techniques

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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*

Inelastic-energy loss to excitation.

Light

Raman*

Brillouin*

X-rays

EXAFS*

Electrons

HREELS*

Ion Scattering*

Neutrons

Inelastic Neutron Scattering

- Brilloin Scattering-Scattering from an acoustic phonon.
- Raman Scattering-Scattering from an optical phonon.

- Fine structure in the vicinity of the adsorption edges contains information about the local environment of the chemical species.

ref: Prof. Brian Tonner, UCF

- 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

- Each method of measurement has advantages specific to the detection method.

ref: Prof. Brian Tonner, UCF

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.

ref: Prof. Brian Tonner, UCF

- 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

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

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

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

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

ref: SNS Website

ref: T.E. Mason

ref: T.E. Mason

- 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

- The contrast mechanism for neutrons scattering length density rather than electron density for x-rays.

ref: T.E. Mason

- Nanoscale lengths are probed.

ref: Charles Glinka, NIST

- The magnetic scattering length in Fe is 1/3 of the chemical scattering length, so SANS also probes magnetic structures.

ref: Charles Glinka, NIST

- Q-dependent reflectivity gives interfacial roughness and correlation length.
- Polarized reflectometry yields magnetic roughness.

ref: T.E. Mason