Single Molecule Spectroscopy Studies of the Nanoscale Properties of Microporous/Mesoporous Silicate Films Prepared by the Sol-Gel Process

州立大学的堪萨斯教授丹尼尔希金斯和玛丽安柯林森得到了分析和表面化学项目的支持，利用单分子光谱学研究了使用溶胶-凝胶工艺制备的微孔硅酸盐薄膜。 这些包括无机硅酸盐、有机改性硅酸盐（ORMOSILS）和含有表面活性剂模板化的中孔的硅酸盐膜。 这些材料正被用于开发新的催化载体、化学传感器和化学分离介质。 要探索的重要的薄膜性能包括局部扩散率的截留分子，当地的pH值和特定位点的变化，在pKa的酸性表面基团，如硅烷醇，和固有的局部极性的硅酸盐基质。 利用pH敏感荧光团的时间和频率分辨光学工作是一个关键的方法。 这些研究还将允许探索无机和有机物富集域的相分离。 在这些研究中需要单分子方法，因为材料是高度异质性的，并且如在体光谱中那样在站点上平均不允许量化类似站点的类型。这项工作的影响在于材料化学、化学分离、催化和传感器开发。 材料内化学位点的表征可以导致更坚固和性能更好的材料。 应用包括环境工程和能源储存。

Professors Daniel Higgins and Maryanne Collinson of Kansas State University are supported by the Analytical and Surface Chemistry Program to study microporous silicate thin films prepared using the sol-gel process using single molecule spectroscopy. These include inorganic silicates, organically modified silicates (ORMOSILS) and silicate films containing surfactant-templated mesopores. These materials are being used to develop new catalytic supports, chemical sensors, and chemical separations media. Important film properties to be explored include local diffusion rates of entrapped molecules, the local pH and site-specific variations in the pKa's of acidic surface groups, such as silanols, and intrinsic local polarity of the silicate matrix. Time- and frequency-resolved optical work utilizing pH-sensitive flurophores is a key approach. These studies will also allow the exploration of phase separation of inorganic and organic-rich domains. Single molecule methods are required in these studies because the materials are highly heterogeneous, and averaging over sites as in bulk spectroscopy does not allow one to quantify types of similar sites.This impact of this work lies in materials chemistry, chemical separation, catalysis, and sensor development. Characterization of the chemical sites within the material can lead to more rugged and better performing materials. Applications include environmental engineering and energy storage.