Effects of organic vapour adsorption on the photoelectron emission from Au thin films in atmospheric air

Photoelectron emission from Au thin films was measured in ambient atmosphere with the presence of various kinds of organic vapours under irradiation of ultaviolet light (254 nm). The photoelectron emission was greatly influenced by the introduction of certain vapours. The observed effects were classified into three types. (i) Alkenes such as cyclohexene gave a large increase of photoelectron current with O-2 in the atmosphere. (ii) Ethanol and water showed moderate and quick increases of the current irrespective of the presence of oxygen. (iii) Acetone reduced the photoelectron current irreversibly to near zero. The work function of Au thin films changed considerably upon the introduction of vapours: a decrease with cyclohexene and an increase with acetone. X-ray photoelectron spectroscopy (XPS) analysis demonstrated that molecular oxygen reacted with cyclohexene to form an oxygenated species on the Au thin films under the irradiation of UV light, which appeared to induce the decrease of the work function of the films.