Identifying the secondary electron cutoff in ultraviolet photoemission spectra for work function measurements of non-ideal surfaces

Absolute values of work functions can be determined in ultraviolet photoemission spectroscopy (UPS) by measuring the minimum kinetic energy of secondary electrons generated by a known photon energy. However, some samples can produce spectra that are difficult to interpret due to additional intensity...

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Bibliographic Details
Published in:Scientific reports 2023-08, Vol.13 (1), p.13452-13452, Article 13452
Main Author: Baddorf, Arthur P.
Format: Article
Language:English
Subjects:
639/301/119
639/301/357
639/301/930
639/925/930/12
Bias
Energy
Humanities and Social Sciences
Kinetic energy
Metals
multidisciplinary
Science
Science (multidisciplinary)
Spectroscopy
Spectrum analysis
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Summary:Absolute values of work functions can be determined in ultraviolet photoemission spectroscopy (UPS) by measuring the minimum kinetic energy of secondary electrons generated by a known photon energy. However, some samples can produce spectra that are difficult to interpret due to additional intensity below the true secondary electron cutoff. Disordered absorbates on elemental metals add small intensity below the onset for the transition metal surfaces studied, which can be attributed to energy losses after photoelectrons are generated. In contrast, spectra from WO 3−x films can produce multiple onsets with comparable intensity which do not fit this model. False onsets (in the context of work function measurements) can be minimized by optimizing experimental detection parameters including limiting analyzer acceptance angles and pass energy. True work functions can be identified by examining the onsets as the sample bias is varied.
ISSN:2045-2322
2045-2322
DOI:10.1038/s41598-023-40187-5