Surface Science and Optical Spectroscopy Studies of Oligothiophene Adsorption on Clean and Oxygen-Dosed Aluminum Surfaces

本项目的目的是研究噻吩齐聚体在表征良好的铝表面上的吸附。将在不同温度下进行X射线和紫外光电子能谱(XPS和UPS)研究，以检查通过将清洁的单晶和多晶铝表面暴露在气相、真空升华或X射线形成的低聚硫吩中而形成的有机层/铝界面。XPS将提供发生在界面上的化学信息，而UPS将用于确定金属的电子价态结构，以及它在低聚硫酚吸附时如何变化。这些结果将与功函数和光谱测量相关联。还将研究不同温度下不同取代的噻吩齐聚物在铝单晶上的吸附，并进行低能电子衍射(LEED)和光致发光，以寻找低聚物有序化的证据。还将进行表面光伏光谱测量，以研究吸收光时费米能级位置的变化。还将研究低聚硫吩共吸附在含氧铝表面和氧化铝表面上的情况，以确定这些表面上的吸附与铝族表面上的吸附有何不同。预计暴露在氧气表面的化学作用较弱，并且应该存在低聚硫吩对齐的可能性。热脱附谱和LEED将被用来评估吸附的低聚物的吸附/脱附行为和有序性。%的铝通常用作聚合物发光二极管(LED)、场效应管和光伏的电极材料，而取代的噻吩类化合物是这类器件的一类重要的聚合物。设备材料对工业非常重要，在这些领域接受培训的学生在就业市场上竞争激烈。该项目由材料研究部的固态化学计划和化学部的先进材料和加工计划共同支持。

The aim of this project is to investigate the adsorption of thiophene oligomers on well-characterized aluminum surfaces are proposed. X-ray and ultraviolet photoelectron spectroscopy (XPS and UPS) studies at a variety of temperatures will be performed to examine the organic layer/aluminum interface formed by exposing clean, single crystal and polycrystalline aluminum surfaces to gas phase, vacuum-sublimed, or x-ray-formed oligothiophenes. XPS will provide information regarding chemistry that is occurring at the interface, and UPS will be used to determine the electronic valence structure of the metal and how it changes upon oligothiophene adsorption. These results will be correlated with work function and optical spectroscopy measurements. Adsorption of a variety of substituted thiophene oligomers will also be studied at different temperatures on single crystals of aluminum, and low energy electron diffraction (LEED) and photoluminescence will be performed to search for evidence of oligomer ordering. Surface photovoltaic spectroscopy measurements will also be carried out to investigate changes in the position of the Fermi level that occur upon absorption of light. Oligothiophene coadsorption on oxygen-dosed aluminum surfaces and on aluminum oxide will also be investigated to determine how adsorption on these surfaces differs from on clan aluminum. Weaker chemical interaction is expected on the oxygen-expose surfaces, and possibilities should exist for oligothiophene alignment. Thermal desorption spectroscopy and LEED will be used to assess adsorption/desorption behavior and ordering of the adsorbed oligomers.%%%Aluminum is commonly used as an electrode material for polymeric light-emitting diodes (LEDs), field-effect transistors and photovoltaics, and substituted thiophenes are an important class of polymers for these types of devices. Device materials are of significant importance to industry, and students trained in these areas compete well in the job market. This project is being jointly supported by The Solid-State Chemistry Program in The Division of Materials Research and The Advance Materials and Processing Program in the Chemistry Division.