你将学到什么
What x-rays are and how are they produced
Interactions of x-rays with matter
Synchrotron and XFEL facilities
Scattering techniques such as diffraction and SAXS
Spectroscopic techniques
Imaging using x-rays
课程概况
Are you interested in investigating materials and their properties with unsurpassed accuracy and fidelity? Synchrotrons and XFELs (X-ray free-electron lasers) are considered to be Science’s premier microscopic tools. They’re used in scientific disciplines as diverse as molecular biology, environmental science, cultural heritage, catalytical chemistry, and studies of the electronic properties of novel materials – to name but a few examples.
This course provides valuable insights into this broad spectrum of scientific disciplines, from the generation of x-rays – via a description of the machines that produce intense x-ray sources – to modern experiments performed using these facilities.
课程大纲
Week 1: General intro of x-rays, synchrotrons, and XFELs:
Introduction including example; X-rays and society; What are synchrotrons and XFELs and why are they so in demand? X-rays and the electromagnetic spectrum.
Week 2: Interactions of x-rays with matter
Interaction of x-rays with matter and the atomic form factor; Relating f to refraction, reflection, and absorption, including subsequent processes (fluorescence, photoelectrons, Auger electrons, secondary electrons)
Week 3: Basics of synchrotron (“machine”) physics
Why accelerated charged particles generate electromagnetic radiation; Properties of relativistic electrons and radiation they emit; Using magnetic fields to steer electrons; RF sources and bunching.
Week 4: Basics of synchrotron (“machine”) physics, continued
Flux, emittance, brilliance, peak brilliance, diffraction limit, and coherence; Magnet lattice: dipoles, quadrupoles, hexapoles, undulators and wigglers; XFEL architecture, SASE, typical properties of XFEL pulses
Week 5: X-ray optics and beamlines
Front-end, mirrors, monochromators, harmonic suppression; Microfocus optics (CRLs, FZPs); X-ray detectors including area detectors and sources of noise; Detectors for XFEL experiments
Week 6: Diffraction and scattering
Why use diffraction? Phase problem; Diffraction at synchrotrons – advantages with examples; Brief recap of description of crystals – Bravais lattice, basis, Miller indices, Bragg’s law, and the Ewald sphere; Typical setups for single-crystal and powder diffraction; Protein crystallography; SAXS and GISAXS
Week 7: UV and x-ray spectroscopy
Need for synchrotron radiation when scanning photon energy. Subsequent processes and their detection; XANES, EXAFS, and STXM with brief examples; STXM and XRF; PEEM/XMCD/XMLD; UPS/ARPES/XPS/HAXPES
Week 8: Imaging techniques
Tomography basics; Phase-contrast XTM and time-resolved XTM; CXDI; Ptychography; Concluding remarks and link to Part II
Week 9: Phasing techniques in macromolecular crystallography
MX has a broad spectrum of tools for tackling the phase problem in structural solutions, including molecular replacement (MR), multiple isomorphous replacement (MIR), multiwavelength anomalous diffraction (MAD), and single-wavelength anomalous diffraction (SAD). These are described in this week’s videos.
预备知识
1st-year undergraduate mathematical concepts.
