Because of the high flux available from third generation soft X-ray be
amlines and the application of high efficiency photodiodes, total fluo
rescent yield spectroscopy is becoming increasingly attractive for obt
aining ground state information in a way similar to X-ray absorption m
easurement. This allows one to tackle systems that are hard to access
with transmission or electron yield methods. A prerequisite, however,
is that one has sufficient understanding of the measurement process. A
recent article (Phys. Rev. Lett. 77 (1996) 1508) based on the insight
s of Thee Thole shows that, in a description in terms of inelastic sca
ttering, the XMCD absorption sum rules should hold also for fluorescen
ce yield in a large number of important cases. In this paper we give s
ome background and illustrate the applicability of the inelastic pictu
re with experimental data. (C) 1997 Elsevier Science B.V.