Photoelectron Diffraction PED

Allied with the diffraction methods, such as low-energy electron diffraction (LEED) and photoelectron diffraction (PED), which can also be applied in single-crystal research, these advances have led to much better interpretations of the vibrational spectra of chemisorbed hydrocarbons in terms of the structures of the surface species. The new results have in turn led to the possibility of reassessing more reliably earlier interpretations of the infrared or Raman spectra of adsorbed hydrocarbons on the finely divided metal samples (usually oxide supported) that are more closely related to working solid catalysts. Such spectra are more complicated because of the occurrence of a variety of different adsorption sites on the metal particles, with the consequence that the observed pattern of absorption bands frequently arises from overlapping spectra from several different surface species. 

Fig. 7. Schematics of photoelectron diffraction, PED. The primary photoelectron is scattered by the surrounding atoms and the subsequent superposition leads to interference and the formation of a diffraction pattern.

PED Photoelectron diffraction [107-109] x-rays (40-1500 eV) eject photoelectrons intensity measured as a function of energy and angle Surface structure... 

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