Work function seen with sub-meV precision through laser photoemission
Work function seen with sub-meV precision through laser photoemission
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DOI：
10.1038/s42005-020-00426-x
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发表时间：
2020-09-11
影响因子：
5.5
通讯作者：
Kobayashi, Y.
中科院分区：
文献类型：
--
作者：
Ishida, Y.;Jung, J. K.;Kobayashi, Y.
电子发射可用于测量表面的功函数。然而，通过电子发射、场发射和光发射技术获得的值中的有效位数通常仅为两个或三个。在这里，我们表明，当应用角度分辨光电子能谱（ARPES）时，这个数字可以达到5。这归功于ARPES的能力，以检测最慢的光电子是直接沿沿着表面法线。通过使用基于激光的源，我们优化了慢光电子的设置，并解决了Au（111）的最慢端截止，其锐度不受光的带宽或费米-狄拉克分布的影响。至少从30至90 K，功函数在+/-0.4 meV内被调平，并且表面老化被识别为功函数的meV偏移。我们的研究开启了对功函数第五位有效数字的研究。功函数是应用于物理学许多方面的基本量，描述了从金属表面移除电子并将其喷射到真空中所需的最小能量。在这里，作者展示了一种方法来确定功函数的五个有效数字，比以前报道的更高的数量级。
Electron emission can be utilised to measure the work function of the surface. However, the number of significant digits in the values obtained through thermionic-, field- and photo-emission techniques is typically just two or three. Here, we show that the number can go up to five when angle-resolved photoemission spectroscopy (ARPES) is applied. This owes to the capability of ARPES to detect the slowest photoelectrons that are directed only along the surface normal. By using a laser-based source, we optimised our setup for the slow photoelectrons and resolved the slowest-end cutoff of Au(111) with the sharpness not deteriorated by the bandwidth of light nor by Fermi-Dirac distribution. The work function was leveled within +/- 0.4 meV at least from 30 to 90 K and the surface aging was discerned as a meV shift of the work function. Our study opens the investigations into the fifth significant digit of the work function.The work function is a fundamental quantity applied to many aspects of physics and describes the minimum energy required to remove an electron from the surface of a metal and eject it into the vacuum. Here, the authors demonstrate a method to determine the work function to five significant figures, a higher order of magnitude than previously reported.