Soft X-ray fluorescence yield XMCD sum rules

Because of the high flux available from third generation soft X-ray beamlines and the application of high efficiency photodiodes, total fluorescent yield spectroscopy is becoming increasingly attractive for obtaining ground state information in a way similar to X-ray absorption measurement. 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 insights of Thee Thole shows that, in a description in terms of inelastic scattering, the XMCD absorption sum rules should hold also for fluorescence yield in a large number of important cases. In this paper we give some background and illustrate the applicability of the inelastic picture with experimental data. (C) 1997 Elsevier Science B.V.