SOFT-X-RAY FLUORESCENCE YIELD XMCD SUM-RULES

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.