Study of 1s3p resonant inelastic x-ray scattering processes in transition metals

G. STUTZ; G. TIRAO

LNLS, Campinas Brasil

Congreso; Activity Report LNLS 2008; 2009

LNLS

Synchrotron radiation sources along with newly developed analyzers based on back-diffracting crystals have made the study of second order x-ray interaction processes,such as the resonant inelastic scattering, with high resolution feasible. Inelastic x-ray scattering in the resonant regime (also called resonant x-ray Raman scattering)can be visualized as an x-ray absorption process followed by x-ray emission, witha virtual intermediate state and a ¯nal state composed of a core-hole in an upperatomic level and an excited electron above the Fermi level. The resonance conditionis achieved tuning the energy of the incident photons close to an absorption edge.Resonant inelastic x-ray scattering spectroscopy (RIXS) can thus yields informa-tion similar to that obtained from x-ray absorption and emission spectroscopies,provided that high energy resolution (i.e. less than or equal to the natural linewidthof the corresponding x-ray transition) is achieved. In recent years, RIXS has becomea powerful technique to investigate electronic excitations and electronic structurein condensed matter. In this work, results from first RIXS studies with high en-ergy resolution made at LNLS are presented. Experiments were performed at theD12A-XRD1 beamline of the LNLS. The experimental setup consists basically ofa sagitally focusing double-crystal monochromator and a spectrometer based on aspherically focusing crystal analyzer in backdiffraction geometry. High energy res-olution along with high transmission of the analyzed beam, required for a modernRIXS experiment, are unique properties of backdiffracting analyzers such as thatused in present study. The mentioned spectrometer was conceived to perform ex-periments with high energy- and momentum-resolution in several regimes of theinelastic x-ray scattering. Whereas 1s2p RIXS processes have been widely studiedin transition metals, the investigation of 1s3p processes, which can provide muchmore rich information about the electronic structure, is scarce. First test measure-ments have shown the feasibility of performing RIXS experiments with high energyresolution at LNLS. In this work results obtained in Cr, Mn, Co, Cu and Zn arepresented. Characteristic features of the resonant inelastic scattering, such as dis-persion of the inelastic peak, peak narrowing and intensity increase close to theresonance condition, were investigated and compared with theoretical predictions.While the strong dependence of the intensity with the incident energy is fairlygood described by the simple independent electron model, this can not accuratelyreproduce the observed energy-dependent linewidth and dispersion.