Standard reference surfaces for work function measurements in air

Determining work functions (WFs) using a Kelvin probe requires a known standard. In air there was no reliable standard until use of electrochemical half-cells was proposed and developed. Here the use of highly oriented graphite, HOPG, is shown to work well as an additional standard, useable in air or vacuum. The values of the WFs of these standards are given, and the precision and accuracy of measurements using them are discussed. Actual examples and some detailed procedures are included.