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

Photoelectron emission from Au thin films was measured in ambient atmospher e with the presence of various kinds of organic vapours under irradiation o f ultaviolet light (254 nm). The photoelectron emission was greatly influen ced by the introduction of certain vapours. The observed effects were class ified into three types. (i) Alkenes such as cyclohexene gave a large increa se of photoelectron current with O-2 in the atmosphere. (ii) Ethanol and wa ter showed moderate and quick increases of the current irrespective of the presence of oxygen. (iii) Acetone reduced the photoelectron current irrever sibly to near zero. The work function of Au thin films changed considerably upon the introduction of vapours: a decrease with cyclohexene and an incre ase with acetone. X-ray photoelectron spectroscopy (XPS) analysis demonstra ted that molecular oxygen reacted with cyclohexene to form an oxygenated sp ecies on the Au thin films under the irradiation of UV light, which appeare d to induce the decrease of the work function of the films.