10.5eV激光在高能量分辨率角分辨光电子能谱中的应用研究

Angle-resolved photoemission spectroscopy (ARPES)is a very powerful method to measure electronic structure at and below Fermi surface as it can provide the energy and momentum resolved spectral function of a solid.Synchrotron and He/Xe lamp are commonly used as ARPES light source, but they have disadvantages like low energy resolution and big focus spot.Light source is the important component in ARPES, so it is very necessary to improve the light source. The advantages of vacuum ultraviolet laser are collimated, coherent,smaller focus size and high energy resolution. We plan to build 10.5 eV laser source through frequency tripling in noble gas.We will focus on the technique of split 118 nm from 355 nm, and apply the 10.5 eV laser on ARPES experiment.The laser will make the energy resolution <1 meV and make the electron mean free paths longer to 1-5 nm, so the bulk sensitivity will be strengthened.

角分辨光电子能谱（Angle-resolved photoemission spectroscopy,ARPES）是研究物质电子结构的最直观的的实验手段之一，光源是ARPES的重要组成部分，而通常采用的同步辐射和He/Xe灯存在能量分辨率低和聚焦光斑大等不足，改善和优化光源对提高ARPES的性能，推动材料科学研究的发展具有重要意义。真空紫外激光与之相比具有方向性和相干性好、光强高、聚焦光斑小、能量分辨率高等优势。本项目拟通过惰性气体中非共振三次谐波的方法产生光子能量为10.5 eV的真空紫外激光，我们将解决激光分束和聚焦等技术问题将其应用到极低温、超高真空度的He3-ARPES上。由于产生三次谐波的基频光的线宽非常窄<0.3 nm，所以10.5eV激光的能量分辨率能达到<1 meV，而且能将电子的平均自由程增加到1-5 nm，大大提高了体效应。同时，缩小激光在样品上的焦点可以提高动量分辨率