|
Several experiments made by Sawatzky et al. in the seventies and
by Thurgate et al. in the nineties on the Auger LMM spectra of the
transition metals showed structures attributed to
L2-L2L3M4,5-M4,5M4,5(M4,5) Coster Kronig
satellites. In particular the APECS (Auger PhotoElectron
Coincidence Spectroscopy) spectra obtained by Thurgate's group on
Ni, Fe, Co and Ga, proved the real existence of these satellites
and showed the fact that they may be expected to be atomic-like
for high hole-hole coulomb interaction or else when the final
state levels are outside the three holes continua, in analogy with
the two hole resonances of the Cini-Sawatzky model. With this work
we set up a model aimed for the calculation of such
line shapes which is still missing at the state of the art today.
To simplify the analysis we started with a closed band situation
treated in an Anderson-like model and we used a two-step model to
describe the Auger decay. The only other assumption we made
consists in taking the one-particle Green's functions appearing in
the theory diagonal in the spin and in the magnetic quantum number
ml . We expect that the presence in the spectra of this kind
of satellites will be closely related to the break of the
independent one-particle picture properly because, to observe the
transition we are interested in, we need that the M4,5
spectator hole doesn't delocalize before the L3 decays. For
this reason the observation of these three-hole satellites is
consistent with an increase in the hole-hole coulomb interaction
due to the incomplete screening of the hole created by the initial
Coster Kronig event and perhaps the spectator hole must be
localized in a two-hole resonance with high probability, which
requires strong correlations. With our model we arrive to an exact
solution of the problem where the equations are very similar to
the ones obtained for the two-hole resonances in the Cini-Sawatzky
theory. We present here preliminary results of this model obtained
assuming a rectangular band for our test-system. |