Sub-threshold photoelectric emission from large area gold plated surfaces

A number of applications require charge neutralisation of isolated test bodies and this has been successfully done using photoelectric emission from surfaces of choice which are electrically benign (gold) or superconducting (niobium). Gold surfaces nominally have a high work function which should require deep UV photons to induce photoemission. In practice it has been found that charge control can be achieved with somewhat lower energy photons. A detailed working understanding of the process has been lacking and this work reports on a study of the photoelectric emission properties of a range of gold plated surfaces using a number of UV light sources of different energies. A model is proposed to explain the observations.