Tang Xiaofeng, Zhou Xiaoguo, Niu Mingli, Liu Shilin, Sun Jinda, Shan Xiaobin, Liu Fuyi, Sheng Liusi
Hefei National Laboratory for Physical Sciences at the Microscale, Department of Chemical Physics, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China.
Rev Sci Instrum. 2009 Nov;80(11):113101. doi: 10.1063/1.3250872.
A novel threshold photoelectron-photoion coincidence (TPEPICO) imaging spectrometer at the U14-A beamline of the Hefei National Synchrotron Radiation Laboratory is presented. A set of open electron and ion lenses are utilized to map velocity imaging of photoelectrons and photoions simultaneously, in which a repelling electric field using an extra lens is applied to magnify images of photoelectrons instead of traditional accelerating electric field in order to suppress the contribution of energetic electrons in the threshold photoelectron spectroscopy (TPES) and the mass-selected TPEPICO spectroscopy. The typical energy resolution of TPES is measured to be 9 meV (full width at half maximum), as shown on the (2)P(1/2) ionization of argon. The measured mass resolving power for the present TPEPICO imaging spectrometer is above 900 of M/DeltaM. Subsequently as a benchmark, oxygen molecule is photoionized by monochromatic synchrotron radiation at 20.298 eV and dissociates to an oxygen atomic ion and a neutral oxygen atom, and the translation energy distribution of oxygen atomic ion is measured by the time-sliced imaging based on mass-selected TPEPICO experiment. The kinetic energy resolution of the present ion velocity imaging is better than 3% of DeltaE/E.
介绍了合肥国家同步辐射实验室U14-A光束线上的一种新型阈值光电子-光离子符合成像光谱仪。利用一组开放式电子和离子透镜同时对光电子和光离子进行速度成像映射，其中使用额外透镜施加排斥电场来放大光电子图像，而非传统的加速电场，以抑制阈值光电子能谱（TPES）和质量选择TPEPICO能谱中高能电子的贡献。如对氩的(2)P(1/2)电离所示，TPES的典型能量分辨率经测量为9 meV（半高宽）。当前TPEPICO成像光谱仪的测量质量分辨能力在M/ΔM为900以上。随后，作为基准，氧分子在20.298 eV的单色同步辐射下被光离子化并解离为氧原子离子和中性氧原子，基于质量选择TPEPICO实验通过时间切片成像测量了氧原子离子的平动能量分布。当前离子速度成像的动能分辨率优于ΔE/E的3%。
