Author Topic: X-ray Satellites spectra in core level 2p peaks of transition metal oxides  (Read 2409 times)

0 Members and 1 Guest are viewing this topic.

IJSER Content Writer

  • Sr. Member
  • ****
  • Posts: 327
  • Karma: +0/-1
    • View Profile
Author : Dr. Sameer Sinha, Vinay Kumar Pandey, Ajay Vikram Singh
International Journal of Scientific & Engineering Research Volume 2, Issue 10, October-2011
ISSN 2229-5518
Download Full Paper : PDF

                    We have used Plasmon theory to explain the Energy Satellites  and relative intensity of transition metal oxides based on their core level peaks. In the photoelectron spectrum, these regions are usually complicated and therefore the choice of the analysis methods can significantly affect the quantification results. In this work, we studied the chemical state quantification of iron and chromium oxides the analysis was based on the 2p region of the photoelectron spectrum and estimated values are in agreement with the calculated values of M. Aronniemi *, J. Sainio, J. Lahtinen

                     X-Ray emission spectra ,X-ray Plasmon Satellite , Iron oxide; Chromium oxide
                In the characteristic X-ray Spectra, Diagram as well as non Diagram lines are present. Those lines which fit in the conventional energy level diagram are called Diagram lines. & those lines which do not fit in the conventional energy level diagram are called non diagram lines. It is also known as “Satellites or Second order lines”. Satellites are generally of weak intensity lines & are found close to more intense parent line. The satellites which are observed on higher energy side are called high energy satellites (HES) whereas those are observed on lower energy side are called lower energy satellites (LES). First Siegbahn & Stenstroem observed these satellites in the K-Spectra of element from Cr (24) to Ge (32) while coster theraeus & Richtmyer in the L-Spectra of element from Cu (29) to Sb (51) & Hajlmar, Hindberg & Hirsch in the M-Spectra of elements from Yb (70) to U (92). Several theories were proposed from time to time to explain the origin of these satellites. Out of these theories the plasmon theory is found to be the most suitable theory especially for those satellites.

Plasmon theory was first proposed by Bohm & pines which are extended by Housten, Ferrel, Noziers & Pines. According to this theory the low energy plasmon satellites are emitted when valence electron excites a plasmon during the annihilation of core hole conversely if Plasmon pre exists, its energy add up to the energy of diagram line.
The radiation less reorganization of electronic shell of an atom is known as Auger effect. Auger satellites have also been observed by Korbar and Mehlhorn [1] Haynes et at. [2] Edward and Rudd [3]. Theoretical explanation for K
series Auger spectrum was given by Burhop and Asaad [4] using intermediate coupling. Later on more refined theory, using relativistic and configuration interaction has been used by Listengarter [5] and Asaad [6]

In Auger primary spectra, one can also observe secondary electron peaks close to the primary peaks are produced by incident electrons which have undergone well energy losses. The most common source of such energy loss in the excitation of collective plasma oscillations of the electrons in the solid. This gives rise to a series of plasma peaks of decreasing magnitude spaced by energy ħp where p is the frequency of plasma oscillation.

                Auger peaks are also broadened by small energy losses suffered by the escaping electrons. This gives rise to a satellite on the low energy of the Auger peak. Energy loss peaks have well defined energy with to primary energy.

              The involvement of Plasmon oscillation in the X-ray emission or absorption spectra of solids has been widely studied during the last few decades and has been recognized that the electron –electron interaction has played an important role.
             This Paper is devoted to  Plasmon theory to explain   the Energy Satellites  and relative intensity  of transition metal oxides (iron and chromium oxides) based on their core level 2p peaks and estimated values are in agreement with the calculated values of M. Aronniemi *, J. Sainio, J. Lahtinen.
        According to Plasmon theory ,  if the valence electron , before filling the core vacancy , also excites a Plasmon ,then the energy ħωp needed for the excitation of Plasmon oscillation is taken from the transiting valence electron so that the emitted radiation will be derived off an energy ħωp and a low energy satellites will emitted whose sepration from the main X-ray line will correspond to ħωp . On the other hand if the Plasmon pre exists , during the X-ray emission process , then , on its decay it can give its energy to the transiting valence electron before it annihilates the core vacancy . Thus the energy of emitted X-ray photon will be higher than the main emission line and by an amount ħωp giving rise to high energy satellite .
      M. Aronniemi, J. Sainio, J. Lahtinen have observed low and high energy satellite peaks in  transition metal oxides (iron and chromium oxides) . A close approximation of their tables shows that some satellites are at a distance of ħωp (Plasmon energy ) from the main emission line  . This observation forced us to think that these might be due to Plasmons emission and absorption .

Read More: Click here...