Work function seen with sub-meV precision through laser photoemission

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