
VOLUME 94  ISSUE 6 
PAGE 466

Qualitative difference between the angular anisotropy parameters in fast electron scattering and photoionization

M. Ya. Amusia^{*°}, L. V. Chernysheva^{°}, E. Z. Liverts^{*}
^{*}Racah Institute of Physics, Hebrew University, 91904 Jerusalem, Israel ^{°}A.F. Ioffe PhysicalTechnical Institute, 194021 St.Petersburg, Russia

Abstract
It is demonstrated for the first time that in spite of well known
big similarities between atomic ionization by photons and fast electrons, a
qualitative difference exists in angular anisotropy parameters of electrons
knocked out in these processes. The difference is disclosed here and
attributed to distinction between normal (transverse) and virtual
(longitudinal) photons. Formulas are derived for dipole and nondipole
angular anisotropy parameters in fast electronatom scattering. The ratio of
quadrupoletodipole matrix elements is determined by the parameter
ω R/υ<1, where ω
is the transferred in collision energy, R is the ionized shell radius, and
υ is the speed of projectile. This factor can be much bigger than in
the case of photoionization, where one has the speed of light c that is much
bigger than υ.
We illustrate general formulas by concrete results
for outer ssubshells of noble gas atoms Ar and Xe. Even for very small
transferred momentum q, in the socalled optical limit, the deviation from
photoionization case is prominent and instructive.


Download PS file (GZipped, 323.7K)

Download PDF file (299.7K)


Список работ, цитирующих данную статью, см. здесь.
List of articles citing this article can be found here.

