vacuum level referencing

https://doi.org/10.1351/goldbook.09361
Method of establishing the kinetic energy scale in which the zero point corresponds to an electron at rest at the vacuum level.
Source:
PAC, 2020, 92, 1781. (Glossary of methods and terms used in surface chemical analysis (IUPAC Recommendations 2020)) on page 1831 [Terms] [Paper]