today is my day for polarization questions...

[Bruce Ravel <ravel@phys.washington.edu>]

Howdy,

Another polarization question found its way into my mailbox today.  I
am passing it along to this list in hopes that someone (say, Alex or
John ;-) will post an authoritative answer, which would be a useful
thing for the archive.

Here is the question:

    I am looking at some grazing incidence data from metals adsorbed
    to a Langmuir monolayer, and I am trying to model it with FEFF
    8.2. Since the monolayer is a 2D powder in the xy-plane, I am
    modeling it with circular polarization in the xy-plane, like

    ELLIPTICITY 1.0 0.0 0.0 1.0
    POLARIZATION 1.0 0.0 0.0

    I was wondering, for an _L3_ edge, does FEFF use the complete
    polarization dependence with the cross-terms between s and d
    states (e.g. as shown in Stohr and Jaeger, Phys Rev B, vol. 27,
    No.8 pp.5146), or does it use some approximation (neglecting some
    terms)?  I looked at the papers that are quoted as references in
    the FEFF manual, and the manual itself, but it does not have
    anything on polarization. I figured you might know something about
    it.

B


-- 
 Bruce Ravel  ----------------------------------- ravel@phys.washington.edu
 U.S. Naval Research Laboratory, Code 6134          phone: (1) 202 767 5947
 Washington DC 20375, USA                             fax: (1) 202 767 1697

 NRL Synchrotron Radiation Consortium (NRL-SRC)
 Beamlines X11a, X11b, X23b, X24c, U4b
 National Synchrotron Light Source
 Brookhaven National Laboratory, Upton, NY 11973

 My homepage:    http://feff.phys.washington.edu/~ravel 
 EXAFS software: http://feff.phys.washington.edu/~ravel/software/exafs/