In-Situ Optical Monitoring for Langmuir/Blodgett Deposition

为创建工程聚合物超薄膜系统（PUFS）创建设计和制造方案的机会可能取决于复杂的原位诊断技术的发展。Langmuir/Blodgett沉积技术为有机材料在光学计算、电子学和生物技术等重要新兴领域的应用奠定了基础。这些应用依赖于对材料特性的精确控制，如活性基团的位置和方向顺序、层的交替和厚度。由于需要研究沉积的聚合物混合物和化合物，以创建具有三维秩序的薄膜系统，因此很明显，需要开发能够跟踪单层从空气/水界面提取时的弹性动力学，水动力学和电动力学行为的方法。在本项目中，我们建议在接触线以及上下静止位置引入激光束。二次谐波发生（SHG）是一种非常有前途的探针，用于研究Langmuir层上分子的取向，以及表征光学高度非线性染料的完整膜系统的顺序。通过将Langmuir层的SHG与基材上的水接触线以及随后在上部静止（干燥）位置获得的SHG进行比较，PI能够通过偏振旋转测量染料部分的重定向，通过振幅变化测量面积/分子的变化，以及通过检查不同分子和基材上的这些相同影响来测量化学降解和干燥。在最初的努力中，PI计划尝试确认这种测量是可能的，并且在验证需要进行进一步研究的时间尺度上正在发生动态。如果这种动态变化是明显的，精确的监测可以允许对槽条件进行精细的调整，以提高薄膜质量。这些测量将提供有价值的信息，目前还没有关于早期单层和后来的层的行为之间的区别。光返回信号将有助于建立朗缪尔层转变为特定沉积单层的过渡历史。如果这项工作取得成功，它将为能够检测薄液体薄膜中构象和键合的细微变化的额外光学和红外光谱开辟道路。

The opportunity to create design and manufacturing protocols for the creation of engineered polymeric ultrathin film systems (PUFS) may well rest on the development of sophisticated, in-situ diagnostics. The Langmuir/Blodgett deposition technique offers the possibility of providing the foundation for the application of organics to important emerging fields, such as optical computing, electronics, and biotechnology. These applications depend on precise control of materials properties such as positional and orientational order of active moieties, alternation of layers, and thickness. With the need to investigate mixtures and compounds of polymers being deposited in order to create film systems possessing three-dimensional order, it has become evident that methods need to be developed capable of tracking the elastodynamic, hydrodynamic, and electrodynamic behavior of the monolayers as they are extracted from the air/water interface. It is proposed in this project to introduce laser beams at the contact line, as well as at the upper and lower resting positions. Second harmonic generation (SHG), which appears to be a very promising probe, is used here to study the orientation of molecules on the Langmuir layer, as well as to characterize the order of completed film systems of optically highly nonlinear dyes. By comparing the SHG from the Langmuir layer with that obtained at the water contact line on the substrate, and later at the upper resting (drying) position, the PI's are able to measure reorientation of the dye moiety through polarization rotation, changes in area/molecule through amplitude changes, and chemical degradation and drying by examining these same effects on different molecules and substrates. In this initial effort, the PI's plan to attempt to confirm that such measurements are possible, and that dynamics are occurring during time scales which validate the need to pursue further study. If such dynamical changes are evident, accurate monitoring may allow delicate adjustment of trough conditions for improved film quality. These measurements will provide valuable information not presently available concerning the distinctions between the behavior of the early monolayers and that of subsequent layers. The optical return signal will aid in establishing the transitional history of the Langmuir layer as it is transformed into a specific deposited monolayer. If this work is successful, it will open the way to additional optical and infrared spectroscopies capable of detecting subtle changes in conformation and bonding in thin liquid films.