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arXiv · 1710.08148

In situ high resolution real-time quantum efficiency imaging for photocathodes

Dai Wu·Dexin Xiao·Jianxin Wang·Qing Pan·Xing Luo·Kui Zhou·Chenglong Lao·Xiangkun Li·Sifen Lin·Peng Li·Hao Zhang·Longgang Yan·Hanbin Wang·Xingfan Yang·Ming Li Chuanxiang Tang·Dan Wang·Qilong Wang·Zhiyang Qi·Jian Zhang
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Abstract

Aspects of the preparation process and performance degradation are two major problems of photocathodes. The lack of a means for dynamic quantum efficiency measurements results in the inability to observe the inhomogeneity of the cathode surface by fine structural analysis and in real time.Here we present a simple and scalable technique for in situ real-time quantum efficiency diagnosis. An incoherent light source provides uniform illumination on the cathode surface, and solenoid magnets are used as lens for focusing and imaging the emitted electron beam on a downstream scintillator screen, which converts the quantum efficiency information into fluorescence intensity distribution. The microscopic discontinuity and the dynamic changes of the quantum efficiency of a gallium arsenide photocathode are observed at a resolution of a few microns. An unexpected uneven decrease of the quantum efficiency is also recorded. The work demonstrates a new observation method for photoemission materials research.

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Dai Wu, Dexin Xiao, Jianxin Wang, Qing Pan, Xing Luo, Kui Zhou, Chenglong Lao, Xiangkun Li, Sifen Lin, Peng Li, Hao Zhang, Longgang Yan, Hanbin Wang, Xingfan Yang, Ming Li Chuanxiang Tang, Dan Wang, Qilong Wang, Zhiyang Qi, Jian Zhang. 2017-10-26. In situ high resolution real-time quantum efficiency imaging for photocathodes. https://arxiv.org/abs/1710.08148

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