New three-dimensional structure analysis with circularly polarized light photoelectron diffraction

本研究的目的是建立一种利用圆偏振光光电子衍射进行三维结构分析的新方法。这里使用的原理是通过左右圆偏振光激发的二维光电子衍射图中前聚焦峰的方位旋转位移来确定光电子散射体和发射体之间的方向和距离。圆偏振光激发光发射过程的研究才刚刚开始，目前所知甚少。本文对圆偏振光在Si（001）表面激发的光发射过程进行了系统的研究。继在动能为几百eV的Si 2p核上进行圆偏振光光电子衍射实验后，在动能为几百eV的Si 2p核上进行了椭圆偏振光光电子衍射实验。接下来，在动能为250 eV的Si 3s-3p价带上进行了圆偏振光光电子衍射实验，考察了初始态的影响。然后测量了Si 3s-3p价带在40 eV左右动能下的光电子角分布，并与高精度理论结果进行了比较。对Si（001）的研究包含了大量的多重散射效应。我们研究了更简化的O/W（110）系统，其中多重散射效应可以忽略不计。实验在美国先进光源实验室进行。实验结果为圆偏振光光电子衍射现象建立了理论基础，并提出了一种新的三维结构分析方法。

The purpose of this study is to develop a new method of three-dimensional structure analysis using circularly polarized light photoelectron diffraction. The principle used here is to determine the direction and the distance between the scatterer and emitter of the photoelectron from the azimuthal rotational shift of the forward-focusing peaks in two-dimensional photoelectron diffraction pattern excited by left and right circularly-polarized light. The study of the photoemission process excited by a circularly-polarized light has just started, and little is understood now. We made several systematic investigation about the photoemission process excited by a circularly-polarized light on Si (001) surface. Following the experiment of circularly polarized light photoelectron diffraction on Si 2p core at kinetic energy of several hundred eV,the experiments of elliptically polarized light photoelectron diffraction on Si 2p core at kinetic energy of several hundred eV were performed. Next, the experiment of circularly polarized light photoelectron diffraction on Si 3s-3p valence band at a kinetic energy of 250 eV was performed to investigate the effect of the initial state. Then the photoelectron angular distribution from Si 3s-3p valence band at a kinetic energy of around 40 eV was measured and compared with highly accurate theoretical results. The studies on Si (001) includes a lot of multiple scattering effect. We studied more simplified system of O/W (110), where the multiple scattering effect can be neglected. The experiment was performed at Advanced Light Source, U.S.A.From all results we could establish a theoretical basis of the phenomena of circularly polarized light photoelectron diffraction, a new method of three-dimensional structure analysis was developed.