US-Poland Joint Fund Research on Reactivity of Silver Clusters in Zeolites

这个美国-波兰玛丽斯克洛多夫斯卡-居里联合 为Jacek博士和 辐射部的Michalik 化学与技术，核研究所 化学和技术，华沙，和拉里博士 北京大学化学系 休斯顿，是在"银团的反应性 在泽维尔。"研究人员将探索 小银团簇作为进入的反应性 进入利用银簇物种 在多相催化中。 关键方面 本研究的目的是控制团簇的大小 在狭窄的范围内。 多种生成方法 导致宽尺寸分布。 一种方法 为了限制这一点， 在分子大小的笼或通道内， 发现于一种叫做沸石的分子筛。 在 除了ESR和相关的光学 光谱学（红外和漫射 反射率），研究人员提出了一种脉冲 电子自旋回波（Electron Spin Echo） 调制（环境扫描电镜）作为一个主要的新工具， 表征银团簇的反应活性 沸石中的物种。 通过分析 弱调制信号 电子-核偶极相互作用，它是 可以确定的协调几何 吸附的顺磁性物质 分子。 在有利的情况下，这应该 提供结构细节，不容易 可通过其他技术获得，例如 吸附物分子的数量， 方向和变化， 配位几何 反应 因此，相当详细的结构 关于反应中间体的信息可以 通过使用ESR，ESEM， 漫反射和红外光谱 这将提高我们对 金属多相催化机理 集群 该项目在辐射化学实现 推进科学发展规划目标 知识，使波兰的领先专家 与美国联合收割机互补 在优势领域集中人才和资源 共同利益和能力。

This US-Poland Marie Sklodowska-Curie Joint Fund research project between Dr. Jacek Michalik of the Department of Radiation Chemistry and Technology, Institute of Nuclear Chemistry and Technology, Warsaw, and Dr. Larry Kevan, Department of Chemistry, University of Houston, is on "Reactivity of Silver Clusters in Zeolites." The researchers will explore the reactivity of small silver clusters as an entry into the utilization of silver cluster species in heterogenous catalysis. The critical aspect of this study is to control the cluster size within narrow range. Many generation methods lead to a broad size distribution. One method to limit this is to produce the metal clusters within a molecular size cage or channel as one finds in molecular sieves called zeolites. In addition to ESR and associated optical spectroscopies (infared and diffuse reflectance), the researchers propose a pulse ESR method known as Electron Spin Echo Modulation (ESEM) as a major new tool in characterizing the reactivity of silver cluster species in zeolites. By analyzing the modulation signal associated with weak electron-nuclear dipolar interactions, it is possible to determine the coordination geometry of paramagnetic species with adsorbed molecules. In favorable cases this should provide the structure details, not readily obtainable by other techniques, such as the number of adsorbate molecules, their orientation as well as the changes of coordination geometry in the course of reaction. Thus, rather detailed structural information about reaction intermediates can be obtained by using a combination of ESR, ESEM, diffuse relectance and infrared spectroscopies which will improve our knowledge about the mechanism of heterogenous catalysis on metal clusters. This project in radiation chemistry fulfills the program objective of advancing scientific knowledge by enabling leading experts in Poland and the United States to combine complementary talents and pool resources in areas of strong mutual interest and competence.