• atoms
  • For isolated atoms, the absorption coefficient decreases monotonically as a function of energy beyond the edge. (springer.com)
  • In transmission experiments, generally drops off monotonically due primarily to the energy dependence of the ionization chamber efficiency and the absorption due to other atoms. (springer.com)
  • Atoms can be excited by a high-energy beam of charged particles such as electrons (in an electron microscope for example), protons (see PIXE) or a beam of X-rays (see X-ray fluorescence, or XRF). (wikipedia.org)
  • threshold
  • Beyond the role of the unoccupied density of states and matrix elements in single electron excitations, many-body effects appear as an "infrared singularity" at the absorption threshold in metals. (wikipedia.org)
  • resonant
  • Relativistic Lorentz contraction bumps the frequency by another factor of γ {\displaystyle \gamma } , thus multiplying the gigahertz frequency of the resonant cavity that accelerates the electrons into the X-ray range. (wikipedia.org)
  • The angle dependence of the x-ray absorption tracks the orientation of resonant bonds due to dipole selection rules. (wikipedia.org)
  • structure
  • Sulfur K-edge X-ray absorption spectroscopy (XAS) is used to investigate the ground-state electronic structure of the resting high-spin and CN- bound low-spin Fe III forms of the 1Fe SOR from Pyrococcus furiosus. (pcom.edu)
  • Metal K-edge Metal L-edge Extended X-ray absorption fine structure Solomon, E. (wikipedia.org)
  • For many years the edge region was referred to as the "Kossel structure" but now it is known as "absorption edge region" since the Kossel structure refers only to unoccupied molecular final states which is a correct description only for few particular cases: molecules and strongly disordered systems. (wikipedia.org)
  • Energy
  • In fluorescence experiments, on the other hand, the baseline rises as a function of energy owing to increasing sample penetration, increased Compton scattering, reduced absorption of the scattering, and other effects. (springer.com)
  • Above the IP the absorption cross section attenuates gradually with the X-ray energy. (wikipedia.org)
  • For instance, in the ultra soft X-ray region (below about 1 keV), crystal field excitations give rise to the energy loss. (wikipedia.org)
  • structural
  • The introduction of pump-probe techniques to the field of x-ray absorption spectroscopy (XAS) has allowed the monitoring of both structural and electronic dynamics of disordered systems in the condensed phase with unprecedented accuracy, both in time and in space. (epfl.ch)
  • electrons
  • The cathode ray tube or an x-ray tube was the method used to pass electrons through a crystal of numerous elements. (wikipedia.org)
  • Techniques
  • Although the advantages of using grazing incidence (GI) techniques in X-ray scattering and spectroscopy have been known for a long time (Yoneda and Horiuchi 1971), the use of such geometry has only been developed fully with the advent of highly collimated X-ray sources, particularly synchrotrons. (geoscienceworld.org)
  • type
  • X-ray absorption spectroscopy (XAS) is ideal in this respect because it is chemically selective and can be implemented in any type of medium. (epfl.ch)
  • XAS is a type of absorption spectroscopy from a core initial state with a well defined symmetry therefore the quantum mechanical selection rules select the symmetry of the final states in the continuum which usually are mixture of multiple components. (wikipedia.org)
  • characterization
  • Dunham, W. R. , Carroll, R. T. , Thompson, J. F. , Sands, R. H. & Funk, M. O. Jr ( 1990 ) The initial characterization of the iron environment in lipoxygenase by Mössbauer spectroscopy , Eur. (wiley.com)
  • atom
  • Though simply defined as x = ( µ - µ o )/ µ o (where μ and µ o are the observed and 'free atom' absorption coefficients, respectively), the determination of x (generally termed as 'background substration') is by no means straightforward since µ o is generally not known. (springer.com)
  • Soft
  • We performed a comparative study of the soft x-ray absorption spectroscopy of the LiMn2O4 and Li1.15Mn1.85O4 electrode materials with a quantitative analysis of the Mn oxidation states. (osti.gov)
  • beams
  • Unfortunately, in the area of x-ray beams, several terms mean exactly the same thing as brilliance. (wikipedia.org)
  • sources
  • When comparing x-ray sources, an important measure of quality of the source is called brilliance. (wikipedia.org)
  • Intensity means power density per unit of area, but for x-ray sources, usually means brilliance. (wikipedia.org)