| Strongly correlated systems, such as, Mott insulator, High Tc superconductor, charge density wave, Giant Magneto Resistence and heavy fermions systems are always the most complicated task in condensed matter physics. In these systems, the competition and cooperation of the freedoms of charge, spin, orbit and lattice bring lots of complicated phenomena and new sates for the system. At present, synchrotron radiation spectroscopy and scattering technique offered a direct and effective experiment probe to understand the electronic structure of the system. It helped to understand and resolve lots of fundamental problems in modern physics. And it has been successfully used in the research of the new electronic materials for the electronic structure, phase transition, orderings and small scale structures etc. Among them, the angle resolved photoemission spectroscopy (ARPES) is the only tool to detect electron's velocity, moving direction and scattering property near Fermi energy in the solid. And these electrons' microcosmic property determined solid's electromagnetic behavior. On the other hand, inelastic x-ray scattering (IXS) detects system's correlation function, and provides excitation's information of the system. In this thesis, we studied the electronic structure of the high Tc superconductor, CDW materials and atoms, small molecules systems. The results are listed below:1. We studied the electronic structure of the cuprate superconductor Bi1.74Pb0.38Sr1.88CuO6+y(Bi2201) . For its low energy structure, we found that the nodal quasiparticle behavior is dominated mostly by phonons, while the antinodal quasiparticle line shape is dominated by spin fluctuations. Moreover, while long range spin fluctuations diminish at very high doping, the local magnetic fluctuations still dominate the quasiparticle dispersion, and the system exhibits a strange metal behavior in the entire overdoped regime. For the high energy structure, we discovered a large scale dispersion of the lowest band, which unexpectedly follows the band structure calculation very well. A giant kink in the dispersion is observed, and the complete self-energy containing all interaction information is extracted for a doped cuprate. These results recovered significant missing pieces in our current understanding of the electronic structure of cuprates.2. We studied the electronic structure of the 2H structured TMD system 2H-NaxTaS2 and quasi-one dimensional CDW material blue bronze K0.3MoO3 and the influence of the tungsten doping , by ARPES. The results are that, two system's spectra are all such broad, not a well defined quasi particle; system still has well defined band structure dispersion, and consistent well with the band calculation. And the CDW all originate form the participation of the electronic states in Fermi patch.3. Electr onic structure of La1-xSr1+xMnO4 system has been studied by ARPES. Experiment results indicate that the charge ordering in the system can be described by auto-correlation analysis to the ARPES spectra. And the charge modulation wave vectors obtained are consistent with other experiment result. This indicates that the origin of the CDW is the participation of the electronic states in Fermi patch.4. We utilized the IXS technique to the study of the exciton structure in C60 system. The low energy extion is consistent with the result from EELS. But excitations in larger energy and momentum transter q window are observed. Especially the behavious of the excitation of 5.8 eV with q, indicates it is not a Plasmon exsitation, as be thought before.5. For the first time, we successfully used IXS technique to study the electronic structure of the atoms and small molecules in gas phase. Especially, on the spectra of the Helium atom, the monopole excitation's intensity is even stronger than dipole excitation in the high momentum transfer q. This experiment is very important to the atoms and small molecules systems' research and also for the technique itself.
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