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

本研究的目的是发展一种利用圆偏振光光电子衍射分析三维结构的新方法。其原理是利用左右圆偏振光激发的二维光电子衍射图中前向聚焦峰的方位角转动位移来确定光电子的散射方向和散射体与发射体之间的距离。对圆偏振光激发的光电子过程的研究才刚刚开始，目前还知之甚少。我们对圆偏振光在Si（001）表面激发的光电发射过程进行了系统的研究。继圆偏振光几百eV光电子衍射实验之后，又进行了椭圆偏振光几百eV光电子衍射实验。接着，为了研究初始状态的影响，进行了Si 3s-3 p价带的250 eV的动能的圆偏振光光电子衍射实验。然后测量了动能为40 eV左右的Si 3s-3 p价带的光电子角分布，并与高精度的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）体系，其中多次散射效应可以忽略。实验是在美国Advanced Light Source公司进行的，实验结果为圆偏振光光电子衍射现象提供了理论依据，为三维结构分析提供了一种新的方法。

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.