X-ray absorption, emission, and photoelectron spectroscopy
Synchrotron-related technologies provide the comprehensive study about the electronic, chemical, and lattice structure owing to the promising features of the monochromatic light, high brightness/resolution, angle-resolvable capability, and element selectivity in the synchrotron center. In soft X-ray technology, the photoelectron spectroscopy describes the chemical structure profile of core level and valence band, due to the photoelectric effect of . The identification for chemical composition and chemical shift have been utilized commonly in the advanced materials science. On the other hands, the absorption spectscopy is corresponding to the profile of electron transition from the core-level electron to the unoccupied state. The polarizted feature is the key to solve the molecular orbital orientation spatially, while the need to define the ordered and layered characterials at an angle on the surface become the controversy over how to affect peroformance.
Resonant inelastic X-ray scattering (RIXS)
For the role of electron/hole transportation and chemical construction in the vicinity of Fermi level, it is in great demand to draw the occupied electronic structure with the elemental determination. Soft X-ray emission (SXE) spectroscopy opens the door not only for understanding the element-related valence band but also the interaction of the intermediate state (the core hole and conduction electron) such as the phonon-, hole-, and electron-electron interactions. It obeys the energy and momentum conservations between photon, electron, phonon, even magnon, during the excitation and radiative decay processes. Several emitted transitions are studied that yield complex behavior as a function of incident X-ray energy for various resonant and non-resonant scatterings. The main one of objectives using the resonant inelastic X-ray scattering (RIXS) is to investigate the electron- and phonon-electron interaction in the novel materials, such as the graphene oxidation/nitrogenation and nanoparticle TiO2 in our Lab. The inelastic scattering (Raman) features are derived from the electron interference at the intermediated state owing to the elemental core-hole life times and X-ray excitation energies. The extrinsic and intrinsic doping introduced into the band structure is important for its chemical and structural modification of novel materials by X-ray absorption and SXE.