Development of Photoelectron Emitting Materials in Ambient Atmosphere

在254 nm的紫外光照射下，测量了Au薄膜在各种有机蒸气存在下的光电子发射。水蒸气的引入对光电子发射有很大的影响。观察到的效应分为三种类型：（i）烯烃，如环己烯，在大气中的O2的光电子电流大幅增加。(ii)乙醇和水表现出温和和快速的电流增加，而不管氧气的存在。(iii)丙酮将光电子电流不可逆地降低到接近零。Au薄膜的功函数在引入蒸汽后发生了很大的变化;环己烯降低，丙酮增加。X射线光电子能谱（XPS）分析表明，在紫外光照射下，分子氧与环己烯在Au薄膜表面生成含氧物种，导致薄膜的功函数下降。

Photoelectron emission from Au thin films was measured in ambient atmosphere with the presence of various kinds of organic vapors under irradiation of ultraviolet light (254 nm). The photoelectron emission was greatly influenced by the introduction of vapors. The observed effects were classified into three types; (i) Alkenes such as cyclohexene gave a large increase of photoelectron current with 02 in the atmosphere. (ii) Ethanol and water showed moderate and quick increases of the current irrespective to 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 vapors ; a decrease with cyclohexene and an increase with acetone. X-ray photoelectron spectroscopy (XPS) analysis demonstrated that molecular oxygen reacted with cyclohexene to form oxygenated species on Au thin films under the irradiation of UV light, which appeared to induce the decrease of work function of the films.