Photoelectron emission from Cs₃Sb coated on a cathode tip

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• 作者：Takayoshi Kimoto^a ; ^{KIMOTO.Takayoshi@nims.go.jp} ; Yoshihiro Arai^b ; Kuniaki Nagayama^c
• 关键词：Photoelectron ; Cs3Sb ; Reaction of Cs and Sb ; Vacuum deposition ; Photocathode for TEM ; Lifetime test
• 刊名：Applied Surface Science
• 出版年：2012
• 期刊代码：6_01694332
• 类别：ms
• 出版时间：15 May, 2012
• 卷：258
• 期：15
• 页码：5646-5653
• 文件大小：725 K

摘要

We developed vacuum deposition equipment for coating a photoemissive material on a cathode tip for TEM in high vacuum. For practical reasons, we firstly examined whether Cs reacts chemically with Sb at low temperature. Photoelectrons were emitted from the as-deposited layers of Sb, Cs and Sb deposited on the cathode tip at 鈭?0 掳C less than 0.5 h after the second Sb deposition. Since the quantum efficiency calculated from the photocurrent was much more than 10⁴ times as large as that of substrate materials, we concluded that Cs₃Sb film was formed by the reaction of Cs and Sb at 鈭?0 掳C. The quantum efficiency of the Cs₃Sb 2 h after the second Sb deposition was 0.021-0.029%, but it decreased rapidly with time at temperatures of both about 鈭?0 掳C and about 10.5 掳C at the vacuum level of 1.2-1.4 脳 10^鈭? Pa. Photoelectrons were successfully detected from the Cs₃Sb coated on a small area of 70 渭m in diameter over the cathode tip whose diameter was 0.2 mm. It was also determined that photoelectrons emitted from Cs₃Sb decreased with anode voltage from 0.1 to 0.4 kV, but increased from 0.4 to 7 kV.