page_title: X-ray emission spectroscopy
section_title: Modern-Spectrometry and the importance of 
    
      
        
          
            K
            
              β
            
          
        
      
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  -lines in the 21st Century
hierarchical_section_title: X-ray emission spectroscopy / Modern-Spectrometry and the importance of 
    
      
        
          
            K
            
              β
            
          
        
      
      {\displaystyle K_{\beta }}
    
  -lines in the 21st Century
caption_attribution_description: English: Normal XAS Measurement against HERFD with incident energy E in eV on x-axis and counts on y-axis
context_page_description: In X-ray emission spectroscopy, X-ray line spectra are measured with a spectral resolution sufficient to analyze the impact of the chemical environment on the X-ray line energy and on branching ratios.
  This is done by exciting electrons out of their shell and then watching the emitted photons of the recombinating electrons.
  It is possible to differentiate between.:
  non-resonant XES
  -measurements
  Valence-to-Core-measurements
  -measurements
  resonant XES
  XAS+XES 2D-measurements
  high-resolution XAS
  2p3d RIXS
  Mössbauer-XES-combined measurements
context_section_description: Today, XES is less used for elemental analysis, but more and more do measurements of -line spectra find importance,
  as the relation between these lines and the electronic structure of the ionized atom becomes more detailed. 
  If an 1s-Core-Electron gets excited into the continuum(out of the atoms energylevels in MO),
  electrons of higher energy orbitals need to lose energy and "fall" to the 1s-Hole that was created to fulfill Hund's Rule.(Fig.2) 
  Those electron transfers happen with distinct probabilities.(see Siegbahn notation)
  Scientists noted, that after an ionisation of a somehow bonded 3d-transition metal-atom the -lines intensities and energies shift
  with oxidation state of the metal and with the species of ligand(s). This gave way to a new method in structural analysis:
  By high-resolution scans of these lines the exact energylevel and structural configuration of a chemical compound can be determined. 
  This is because there are only two major electron transfer mechanisms, if we ignore every transfer not affecting valence electrons. 
  If we include the fact that chemical compounds of 3d-transition metals can either be high-spin or low-spin we get 2 mechanisms for each spin configuration.
  These two spin configurations determine the general shape of the  and -mainlines as seen in figure one and two,
  while the structural configuration of electrons within the compound causes different intensities, broadening, tailing and piloting of the  and -lines.
  Although this is quite a lot of information, this data has to be combined with absorption measurements of the so-called "pre-edge" region. 
  Those measurements are called XANES(X-ray absorption near edge structure).
  In Synchrotron facilities those measurement can be done at the same time,
  yet the experiment setup is quite complex and needs exact and fine tuned crystal monochromators to diffract the tangential beam coming from the electron storage ring.
  Method is called HERFD, which stands for High Energy Resolution Fluorescence Detection.
  The collectionmethod is unique in that, after a collection of all wavelengths coming from "the source" called ,
  the beam is then shone onto the sampleholder with a detector behind it for the XANES part of the measurement.
  The sample itself starts to emit X-rays and after those photons have been monochromatized they are collected, too. 
  Most setups use at least three crystal monochromators or more.
  The  is used in absortption measurements as a part of the Beer-Lambert Law in the equation
  where  is the intensity of transmitted photons.
  The received values for the extinction  are wavelength specific which therefore creates a spectrum of the absorption. 
  The spectrum produced from the combined data shows clear advantage in that background radiation is almost completely eliminated while still having an extremely resoluted view on features on a given absorption edge.(Fig.4)
  In the field of developement of new catalysts for more efficient energy storage,production and usage in form of hydrogen fuelcells and new battery materials,
  the research of the -lines is essential nowadays.
  The exact shape of specific oxidation states of metals is mostly known, yet newly produced chemical compounds with the potential 
  of becoming a resonable catalyst for electrolysis, for example, are measured every day. 
  Several countries encourage many different facilities all over the globe in this special field of science in the hope for clean, responsible and cheap energy.
caption: Fig.4: XAS Measurement against HERFD
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