热离子发射
超短脉冲
材料科学
光电阴极
工作职能
超快电子衍射
电子
反射高能电子衍射
光电子学
电子衍射
激光器
原子物理学
分析化学(期刊)
光学
化学
纳米技术
衍射
物理
图层(电子)
量子力学
色谱法
作者
Xuefei Guo,Dipanjan Chaudhuri,Nina Bielinski,Jin Chen,Soyeun Kim,Tai C. Chiang,Fahad Mahmood,Julio A. N. T. Soares,Siddharth Karkare,Peter Abbamonte
摘要
There is a widespread interest in time-resolved electron spectroscopies such as ultrafast electron diffraction, ultrafast electron microscopy, and ultrafast electron energy loss spectroscopy. These techniques require pulsed electron beams with both high current and brightness. LaB6 is commonly used as a thermionic emitter because of its low work function and high electron yield. However, its use as a pulsed photocathode has not been widely explored. Here, we present measurements of the electron yield from a LaB6 filament exposed to 392 nm UV ultrafast laser pulses under a wide range of filament temperatures. We find that sample heating strongly enhances photoelectron yield, an effect known as thermionically enhanced photoemission. However, it also creates potentially undesirable, continuous thermionic background. We conclude that the ideal optimal operating conditions strongly depend on the type of measurement and require defining and quantifying an appropriate figure of merit.
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