Laser Spectroscopy of New Fullerene and Metallofullerene Optical Materials

摘要：本研究旨在了解不同种类的富勒烯及其非线性性质与电子结构之间的关系。提议的工作将包括创建新的衍生物和材料的例子，可以探索了解与其他部分的相互作用如何改变电子和光学性质。很明显，中性富勒烯没有有趣的非线性，而富勒烯和富勒烯衍生物家族中最有趣的成员是带电离子、电荷转移配合物和内质金属富勒烯。该研究将继续有两个重要部分：新的富勒烯基材料的合成、纯化、制备和表征以及这些材料的新光学性质的测量。光学测量的核心将集中在利用多共振四波混合光谱的能力来识别导致非线性的状态，探测电子状态之间的转变和耦合，并确定由允许电荷转移转变的内腔金属或外部部分引起的新状态的特征和有用性。由于富勒烯和金属富勒烯材料的稳定性、非线性性质、电荷转移特性以及通过改变价态、笼的大小、内嵌离子的数量和类型来操纵其性质的能力，人们对其光学性质非常感兴趣。衍生化，以及与其他富勒烯的连接。可能的材料包括电荷转移盐、纳米级表面结构和薄膜、沸石和聚合物材料。新型光学材料的开发需要了解富勒烯性质的变化如何影响材料的光学和电学转移特性。先前拨款期间的工作已经清楚地表明，中性富勒烯不会是使光子学领域具有竞争力的神奇非线性材料。它们的非线性比该领域的工作人员所希望和测量的要小得多。然而，阴离子的非线性是实质性的，它们可以通过这里提出的想法和通过形成加强极化性的衍生物而大大改善。富勒烯也是一种不寻常且有趣的材料，因为它能够通过控制笼中碳的数量、价态、内嵌金属离子以及形成富勒烯衍生物来设计它们的电子结构。除了用于非线性材料之外，富勒烯的正常电子和电荷转移态对许多有趣的潜在用途至关重要，包括光折变、光导、光伏、空穴燃烧存储和激光材料。本项目将重点研究带电富勒烯和内嵌金属富勒烯不同价态的电子结构特征。

Abstract 9632993 Wright This research is concerned with understanding the relationship between the different kinds of fullerenes, their nonlinear properties, and their electronic structure. The proposed work will involve creating examples of the new derivatives and materials that can be probed to understand how the interaction with other moieties changes the electronic and optical properties. It is clear that the neutral fullerenes do not have interesting nonlinearities and that the most interesting members of the fullerene and fullerene derivatives family are the charged ions, charge transfer complexes, and the endohedral metallofullerenes. The proposed research will continue to have two important parts: synthesis, purification, preparation, and characterization of new fullerene-based materials and measurement of the novel optical properties of these materials. The heart of the optical measurements will concentrate on using the capabilities of multi-resonant four wave mixing spectroscopy to identify the states that are responsible for the nonlinearities, to probe the transitions and coupling between electronic states, and to determine the character and usefulness of the new states that are caused by having endohedral metals or external moieties that allow charge transfer transitions. %%% There is great interest in the optical properties of materials that are based on fullerenes and metallofullerenes because of their stability, nonlinear properties, charge transfer characteristics and the ability to manipulate their properties through changes in the valence state, the size of the cage, the number and type of endohedral ions. the derivatization, and the linking with other fullerenes. The possible materials include charge transfer salts, nano-scale surface structures and films, zeolytes, and polymeric materials. Development of new optical materials requires an understanding of how changes in the nature of the fullerene affect the material's optical and electr on transfer properties. Work during a prior grant period has made it clear that the neutral fullerenes will not be the magic nonlinear material that will make the field of photonics competitive. Their nonlinearities are much smaller than the workers in the field had hoped for and measured. Nevertheless, the nonlinearities of the anions are substantial and they may be improved considerably by the ideas presented here and by forming derivatives that accentuate the polarizability. The fullerenes are also unusual and intriguing materials because of the ability to engineer their electronic structures by manipulating the number of carbons in the cage, the valence state, the endohedral metal ion and by forming fullerene derivatives. In addition to their promise for nonlinear materials, the normal electronic and charge transfer states of fullerenes are central to many interesting potential uses including photorefractive, photoconductive, photovoltaic, hole burning storage, and laser materials. The program during this grant period will focus on the electronic structures characteristic of the different valence states of the charged fullerenes and the endohedral metallofullerenes.