Absorption Spectrum of Beryllium in the Neighborhood of theKEdge

X-Ray Interactions: Photoabsorption, Scattering, Transmission, and Reflection at E = 50-30,000 eV, Z = 1-92

“…At energies near the absorption edges the photoabsorption cross section is found_ to depend on the chemical environment of the atom since transitions are to weakly bound excited states or to unbound shape resonances giving rise to near edge x-ray absorption fine str~cture (NEXAFS) [36]. At energies somewhat higher than this there are weaker oscillations in the cross section as a function of energy resulting from the backscattering of the outgoing wavefunction of the photoelectron (EXAFS) from neighboring atoms.…”

“…This yields the expression, r'2 Uinc = 211'r~ lo d9sin29(1 + cos 2 29)(Z-f;jz). (36) Because the differential solid angle in this integral includes all scattering planes, this result is independent of the polarization state of the incident beam.…”

A Bridge between Conceptual Frameworks

“…yet, they promoted not only the use of synchrotron radiation (sr), but also the reactivation of studying XAs basic theory. (Johnston andtomboulian (1954, p. 1589) , Fig. such a long time delay had several good reasons: the conventional source was much cheaper, and had the advantage of being stable and reliable, besides being at home.…”

Fifty years since the first European synchrotron-radiation-derived XAFS spectrum (Frascati, 1963)

“…Moreover, Cauchois et al (1963a, p. 402) could proudly boast that their results were the first obtained at relatively high energies and by using a crystal analyser, whereas the only two previously published XAS results using synchrotron radiation [the Be K-edge at 112 eV and the Al L III -edge at 72.8 eV (Tomboulian & Hartman, 1956), and the absorptions of gases in the energy range 26-69 eV (Madden & Codling, 1963)] that they were aware of, both obtained in the USA, were at much lower energy. Surprisingly, Cauchois disregarded, or was unaware of, the very early experiment conducted by Johnston & Tomboulian in 1954(Johnston & Tomboulian, 1954. Indeed, this extraordinary precocious experiment had given to the physics community the first demonstration of an XAS spectrum recorded from polychromatic synchrotron radiation.…”

“…Surprisingly, Cauchois disregarded, or was unaware of, the very early experiment conducted by Johnston & Tomboulian in 1954(Johnston & Tomboulian, 1954. Indeed, this extraordinary precocious experiment had given to the physics community the first demonstration of an XAS spectrum recorded from polychromatic synchrotron radiation.…”