Soft X-Ray Spectroscopic Studies of Mixed Valence 4f Electronic States in Rare Earth Compounds

(1)CeRh_3B_2的Ce 3d吸收光谱偏振依赖性的测量CeRh_3B_2是一种具有六方晶系结构的铁磁体，由于它具有很高的居里温度，即居里温度，因此人们对其进行了大量的研究。例如，T_o =112K。光电子能谱分析表明，它是一种混合价材料，基态4f电子数n_f = 0.85-0.90。CeRh_3B_2中的Ce原子沿c轴沿着成链状排列，且在此方向上的Ce-Ce间距远小于在c平面上的Ce-Ce间距。因此，平行于和垂直于CeRh_3B_2的六方c轴的偏振态在Ce 3d x射线吸收谱上存在差异。测量将于今年4月在KEK-PF举行。(2)软x射线探测用平行板雪崩室的新进展。在体晶体的情况下，用总电子产额法测量了吸收光谱。射出的光电子对表面状况非常敏感。另一方面，荧光X射线对于检测散装材料非常有用。为了检测荧光X射线，使用气流正比室。为此，设计了低压平行板雪崩室，并进行了试验。(3)电子能量损失谱仪。众所周知，电子能量损失谱（EELS）提供与软X射线吸收谱（XAS）相同的信息。反射式能量损失谱仪是固体物理研究中的一种有用工具。到目前为止，已研制出静电双聚焦能量分析器，并设计了电子枪和透镜系统。项目正在进行中。

(1) Measurement of polarization dependency in Ce 3d absorption spectra of CeRh_3B_2. CeRh_3B_2 is known to be a ferromagnet with a hexagonal crystal structure, and many studies have been carried out on the compounds since it has a high Curie temperature, i. e., T_o =112K. It is also known as a mixed valence material with the number of 4f electrons n_f in the ground state as n_f = 0.85-0.90, from the result of photoemission spectroscopy. The Ce atoms in CeRh_3B_2 form linear chains along the c-axis, and the interatomic Ce-Ce distance in this direction is much smaller than that in the c-plane. So, a difference in the Ce 3d x-ray absorption spectra between polarization parallel and perpendicular to the hexagonal c-axis of CeRh_3B_2 is expected. The measurement is held this April at KEK-PF.(2) New development of parallel plate avalanche chamber (PPAC) for detection of soft x-ray. In the caseo f bulk crystals, the absorption spectra were measured by total electron yield method. The ejected photoelectron is very sensitive to the surface condition. On the other hand, the fluorescent x-ray is very useful to detect the bulk materials. In order to detect the fluorescent x-ray, gas flow proportional chamber is used. For this purpose, the low pressure parallel plate avalanche chamber is designed and now test operated.(3) Electron energy loss spectrometer. It is well known that the electron energy loss spectra (EELS) provide the same information as the soft x-ray absorption spectra (XAS). The reflection type energy loss spectrometer is a useful research tool for use in solid state physics. Until now, the electrostatic double focusing energy analyzer was made and the electron gun and lens systems are designed. A project is in progress.