Precise measurement of the work function (Φ) is crucial for understanding surface electronic structures and various surface phenomena. Traditional thermionic, field, and photoemission techniques typically yield Φ values with only two or three significant digits. This study demonstrates that angle-resolved photoemission spectroscopy (ARPES) using a laser-based source can achieve sub-meV precision in work function measurements, reaching up to five significant digits. By optimizing the setup for slow photoelectrons emitted along the surface normal, the authors resolved the slowest-end cutoff of Au(111) with exceptional sharpness. The work function remained stable within ±0.4 meV from 30 to 90 K, highlighting the high precision of the method and enabling the detection of surface aging as a meV shift in Φ.

Y. Ishida, J. K. Jung, M. S. Kim, J. Kwon, Y. S. Kim, D. Chung, I. Song, C. Kim, T. Otsu, Y. Kobayashi