Structure-Property Relations for Nonlinear Optical Materials

计划对材料的结构/非线性光学性质关系进行积极的研究，特别强调几类有机化合物。一个优秀的专家合作团队已经在这一领域聚集沿着最好的实验设施的非线性光学（NLO）材料表征。沿着CREOL的PI（包括一名化学家），合作者包括亚利桑那大学化学系的Seth Marder、Joseph佩里和Jean-Luc Bredas，苏黎世ETH化学系的Francois Diederich，乌克兰基辅国家科学院物理研究所的Olga Przhonska、Alex Kachkovski和同事，以及佛罗里达大学的Anthony Brennan。国家的最先进的实验室设施已专门设计和开发的方案中概述的这一建议。 五个实验室致力于这项研究。最新增加的是飞秒泵浦/连续探测器，非线性“分光光度计”。 这模拟了标准线性分光光度计的操作，并且是最接近可以制成用于NLO材料特性的光谱分析的商业仪器的设施。 数据与双光子荧光（2 PF）光谱法，这需要相当长的时间，需要荧光样品是一致的。因此，可以研究更广泛的材料。这些技术与PI先前开发的实验Z扫描技术相结合，沿着使用飞秒、皮秒和纳秒可调谐光学参量源的单频泵浦-探测方法的互补方法，提供了一种独特的设施来实现所提出的努力的目标。 本研究的最终目标是开发一个预测能力的非线性光学性质的线性光学性质和/或分子结构类似的PI已经完成的半导体。 飞秒连续谱的波长范围可以从300 nm到1.7 mm，因此可以在这个宽光谱范围内探测NLA。因此，在单个实验中，测量从IR到UV的所有频率下的吸收变化。 通过时间延迟探针，这种非简并NLA的动力学也得到了。 这使得双光子吸收的超快NLA过程与累积非线性（如激发态吸收）容易分离。 用这种仪器可以确定强双光子吸收带在哪里，以及激发态吸收光谱是什么。对这些问题和类似问题的回答将为理论家提供必要的信息，以测试理论和实践者发现和利用新的NLO材料。

An aggressive investigation is planned on the structure/nonlinear optical property relations of materials with special emphasis on several classes of organic compounds. An excellent collaborative team of experts has been assembled in this area along with the best experimental facilities for nonlinear optical (NLO) materials characterization. Along with the PI's at CREOL including a chemist, collaborators include Seth Marder, Joseph Perry and Jean-Luc Bredas with Chemistry at the University of Arizona, Francois Diederich in Chemistry at ETH, Zurich, Olga Przhonska, Alex Kachkovski and co-workers at the Institute of Physics, National Academy of Sciences, Kiev, Ukraine, and Anthony Brennan at the University of Florida. State-of-the-art laboratory facilities have been specifically designed and developed for the program outlined in this proposal. Five laboratories are devoted to this investigation. The latest addition is a femtosecond pump/continuum probe, nonlinear "spectrophotometer". This mimics the operation of a standard linear spectrophotometer and is the closest one can come to a facility that could be made into a commercial instrument for spectral analysis of NLO material properties. Data are consistent with the two-photon fluorescence (2PF) spectroscopy method, which takes considerably longer and requires fluorescent samples. Thus, a broader range of materials can be studied. These techniques, combined with the PIs' previously-developed experimental Z-scan technique, along with complementary methods of single frequency pump-probe methods with femtosecond, picosecond, and nanosecond tunable optical parametric sources, provide a unique facility to carry out the goals of this proposed effort. The ultimate goal of this study is to develop a predictive capability for the NLO properties in terms of the linear optical properties and/or molecular structure similar to what the PIs have accomplished for semiconductors. The femtosecond continuum can range in wavelength from 300 nm to 1.7 mm and can thus probe the NLA over this broad spectral range. Thus, in a single experiment the changes in absorption at all frequencies from the IR to the UV are measured. By temporally delaying the probe, the dynamics of this nondegenerate NLA are also obtained. This allows easy separation of the ultrafast NLA process of two-photon absorption from cumulative nonlinearities such as excited state absorption. With this instrument one can determine where are the strong two-photon absorption bands, and what is the excited-state absorption spectrum. The answers to these and similar questions will give theoreticians the information necessary to test theories and practitioners to find and exploit new NLO materials.