Physics of electromagnetic radiation in the ~100 eV – 100 keV range and its interaction with matter. Sources: X-ray tubes (Bremsstrahlung + characteristic lines), synchrotron bending magnets and insertion devices (wigglers, undulators),…
x-ray-physics
XFEL SASE: micro-bunching instability in an undulator gives coherent X-rays
Kondratenko-Saldin 1980 / Pellegrini 1992 self-amplified spontaneous emission (SASE): a relativistic electron bunch (γ ≈ 17000 for 9 GeV,…
EXAFS / XANES: Sayers-Stern-Lytle oscillations give local atomic structure
Sayers-Stern-Lytle 1971 extended X-ray-absorption fine structure (EXAFS): above an inner-shell absorption edge (K, L) the photoelectron…
Multilayer X-ray mirror (Bragg reflector, Spiller 1972)
Spiller 1972 multilayer X-ray mirror: alternating layers of high-Z (Mo, W, Ni) and low-Z (Si, C, B₄C) materials with layer-pair thickness d…
Bragg law: 2d sin θ = nλ (W.L. & W.H. Bragg 1913, Nobel 1915)
W.L. Bragg & W.H. Bragg (father-and-son) 1913 Bragg law (Nobel Prize in Physics 1915): X-rays of wavelength λ incident on a crystal with…
Compton shift: Δλ = (h/m_ec)(1 − cos θ) = λ_C(1 − cos θ)
Compton 1923 (Nobel 1927): X-ray photons of wavelength λ scattered by free electrons at rest at angle θ from the incoming direction have…
Thomson cross-section: σ_T = (8π/3)r_e² ≈ 0.6652 barn
Thomson cross-section for elastic low-energy (ℏω ≪ m_ec²) photon-electron scattering: σ_T = (8π/3)r_e², where r_e = e²/(4πε₀ m_e c²) ≈…