Soft-X-ray fluorescence studies of solids

Resonant inelastic X-ray scattering (RIXS) has been observed in many system s above and below their core threshold. Below threshold, inelastic-loss fea tures are observed, which disperse linearly with excitation energy, but as the excitation increases above the core binding energy, nonlinear dispersiv e effects are observed. These two effects are described by the same physics of coherent fluorescence. Very good agreement between experiment and simul ated RIXS is achieved using a simple one-electron framework. However, signi ficant questions have arisen concerning core-hole effects and their influen ce on RIXS. In this work, the role core-excitons play in the RIXS process i s examined in finer detail in graphite, by using narrow-band excitation, an d through comparison between experiment and simulated spectra which include the core-hole effects explicitly in the modeling. Based on these findings, we conclude that core-hole effects play a minor but detectable role in the RIXS observed from graphite. (C) 1999 Elsevier Science B.V. All rights res erved.