Impact of the photoelectric threshold sensitivity on the work function determination—Revealing ultra-low work functions of caesiated surfaces

The exploitation of the photoelectric effect is a prominent method for in situ measurement absolute work function surface. In case metallic surfaces, Fowler theory routinely applied fitting or extrapolating measured yield data to determine value. However, reliable application method, attention must be paid experimental sensitivity behavior close threshold, which mainly determined by signal-to-noise ratio photocurrent detection and available photon energies used irradiation. This illustrated means applying system during Cs coating process metal surface, where insufficiently low an unfavorable noise level can lead severe overestimation order 1 eV. By sufficient enhancement sensitivity, it now unveiled that ultra-low surface functions 1.25 ± 0.10 eV generated via caesiation surfaces (here molybdenum stainless steel) under vacuum conditions 10 ?6 –10 ?5 mbar, most probably result formation oxidized adlayer.