Nonobservability of Born Approximation Structures in GOSs.
Abstract
We explain the unfeasibility of observing experimentally the complicated structure of Generalized oscillator strengths (GOS's), which are calculated in the first Born approximation (FBA), demonstrating that FBA calculations are not valid in the vicinity of the minima even at very high nonrelativistic electron impact energies. The differences between the FBA and CCC numerical results for the 6s → 6p ^1P_{0} transition in Ba have been accounted for through examination of the real and imaginary parts of the scattering amplitude, as a function of momentum transfer, for different electron impact energies. Our calculations of the scattering amplitude demonstrate that, while with increasing energy of the initial electron the imaginary part of the amplitude rapidly converges to the amplitude obtained in FBA, the real part does not diminish significantly, giving a big increase of GOS in comparison with the plane wave approximation predictions. An exception is the region of small momentum transfer, which however are usually in an experimentally inaccessible nonphysical region of the scattering angle.
 Publication:

APS Division of Atomic, Molecular and Optical Physics Meeting Abstracts
 Pub Date:
 May 2003
 Bibcode:
 2003APS..DMP.J1065A