Work function seen with sub-meV precision through laser photoemission

Abstract

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 $\pm$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.

For an associated blog-type posting, see https://devicematerialscommunity.nature.com/posts/measuring-the-work-function-precisely-by-using-laser-arpes

References in corpus (5)

• Laser ARPES, the sudden approximation, and quasiparticle-like peaks in Bi2Sr2CaCu2O8+delta
• Time-resolved photoemission apparatus achieving sub-20-meV energy resolution and high stability
• Detailed band structure of twinned and detwinned BaFe${}_2$As${}_2$ studied with angle-resolved photoemission spectroscopy
• High repetition pump-and-probe photoemission spectroscopy based on a compact fiber laser system
• Particle-hole Asymmetry in the Cuprate Pseudogap Measured with Time-Resolved Spectroscopy