Small Molecule Photodissociation in Solid Parahydrogen

怀俄明州大学的大卫安德森得到了实验物理化学计划的支持，他的研究旨在通过实验验证化学在分子氢的低温晶体中可以停止到什么程度。 以低浓度添加到氢晶体中的化学杂质将原位光化学转化为活性物质，例如自由基。 一旦通过红外光谱显示活性物质被捕获在固体氢中，激光激发将用于在高度受控的条件下引发化学反应，以在分子水平上探索低温凝聚相反应动力学的细节。 两个重要的自由基的目标物种是亚胺基自由基（NH）和羟基自由基（OH），其与分子氢在低温氢矩阵的反应将被研究。 用于氢基质研究的其他可能的自由基包括NO、甲基自由基和CN。 预计项目成果将提供化学和物理信息，用于从第一原理预测新型低温凝聚氢中激光引发化学反应的结果。冻结的分子氢是一种不寻常的凝聚材料，因为在它凝固的低温下，氢的晶体性质由量子力学行为决定。 安德森对固体氢反应的研究将测试低温凝聚相化学的基本概念，提供对木星等行星内部和表面化学（或缺乏化学）的见解，并可能允许控制化学反应途径的新方法。

David Anderson of the University of Wyoming is supported by the Experimental Physical Chemistry Program for research to verify experimentally to what extent chemistry can be halted in cryogenic crystals of molecular hydrogen. Chemical impurities added to hydrogen crystals at low concentrations will be photochemically transformed in situ into reactive species such as radicals. Once the reactive species are shown to be trapped in solid hydrogen by infrared spectroscopy, laser excitation will be used to initiate chemical reactions under highly controlled conditions in order to explore low temperature condensed phase reaction dynamics at a molecular level of detail. Two important radical target species are the imidogen radical (NH) and the hydroxyl radical (OH), whose reactions with molecular hydrogen in the cryogenic hydrogen matrix will be studied. Other possible radicals for hydrogen matrix study include NO, methyl radical, and CN. Project outcomes are expected to provide chemical and photophysical information useful for predicting outcomes of laser initiated chemical reactions in novel low temperature condensed hydrogen from first principles. Frozen molecular hydrogen is an unusual condensed material, since at the low temperatures at which it solidifies, the hydrogen crystal properties are dominated by quantum mechanical behavior. Anderson's studies of reactions in solid hydrogen will test the fundamental concepts involved in low temperature condensed phase chemistry, provide insights into chemistry (or lack of it) occurring in and on the surface of planets such as Jupiter, and potentially allow for new ways of controlling chemical reaction pathways.