Angle-Resolved Photoemission Spectroscopy (ARPES) maps the dispersion of electronic bands near the Fermi level and, in particular, the Fermi surface itself by exciting the bound electrons in a metal with a given photon energy hv.
Use of Pilatus 2M with long camera lengths. Detector positioning system and the GISAXS flight tube.
Surfaces and interfaces determine many of the properties of materials, including electronic, magnetic and chemical behaviour. Experiments carried out at existing 3rd generation synchrotron sources have focused on well defined samples in artificial environments. However, surface and interface diffraction techniques such as Grazing Incidence X-ray Diffraction (GIXD) are also ideal tools for determining the morphology of novel materials in realistic operating conditions.
Often called Non-crystalline diffraction (NCD), Small Angle X-ray Scattering provides essential information on the structure and dynamics of large molecular assemblies in low ordered environments. These are characteristic of living organisms and many complex materials such as polymers and colloids. Small angle scattering covers the angular range up to 1° while WAXS typically covers 5 - 60°. Anomalous SAXS (ASAXS) takes advantage of the tuneable nature of synchrotron X-rays, using X-rays with energies close to the absorption edges of the element under study. This provides information on the specific composition and density fluctuation of the sample.
Spectroscopic experiments allow researchers to reveal elemental composition, chemical state and physical properties of both inorganic material and biological systems. By sweeping through a range of photon energies the absorption, reflectivity or fluorescence of the sample is measured. In the X-ray region all atoms absorb X-rays sharply at certain wavelengths (called absorption edges) that are characteristic of that atomic species, so element-specific information can be obtained.
A range of X-ray Absorption Spectroscopy (XAS) techniques are available at Diamond, including X-ray Absorption Near-Edge Structure (XANES), Extended X-Ray Absorption Fine Structure (EXAFS), Resonant Inelastic X-Ray Scattering (RIXS) and X-Ray Emission Spectroscopy (XES).
Diffraction and scattering techniques analyse the patterns produced when a sample is illuminated by X-rays and causes deflections. Diffraction patterns provide the atomic structure of molecules such as powders, small molecules or larger ordered molecules like protein crystals.
X-ray Magnetic Circular Dichroism (XMCD) uses the differential absorption of left and right circularly polarised light in a magnetic field to examine magnetic materials and properties. This includes the behaviour of bulk materials, thin films and multilayers, magnetic nanostructures and clusters, and spin transport systems.
Diamond Light Source is the UK's national synchrotron science facility, located at the Harwell Science and Innovation Campus in Oxfordshire.
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