Mechanistic Organic Chemistry of Relevance to the Interstellar Medium

威斯康星州-麦迪逊大学化学系的Robert J. McMahon教授获得了有机和大分子化学计划的支持，他的研究旨在阐明星际空间中有机分子的身份，结构，性质和反应性。实验和计算研究的结合集中在已知或可能存在于星际介质中的有机物种上。这些有机物种将在实验室中产生，并通过红外，紫外/可见光，电子自旋共振和微波光谱法研究其分子结构。为了解决星际空间中环状芳香族物质存在的问题，以及它们从已被证明存在的无环分子形成的机制，将研究开链有机分子进行环闭合的基本化学机制。进一步的研究将试图通过实验室旋转光谱学和随后的射电天文学搜索相结合的方法来探测星际介质中的芳香族物质及其前体，所谓的“弥漫星际带”的起源被认为是现代天文学和分子光谱学的基本问题之一。目前，我们还不确定星际空间中是否存在具有不寻常的稳定性（称为芳香性）的环状物质，如果存在的话，这些物质是如何从已知存在于星际空间的非环状分子中形成的。在有机和高分子化学计划的支持下，威斯康星州-麦迪逊大学化学系的Robert J. McMahon教授正在进行旨在解决这些问题的实验和计算研究相结合。通过制备芳香族物质的无环前体并检查它们的结构和反应性，McMahon教授探索了可能在星际空间发生的基本反应化学。通过用各种光谱技术探测这些物种，他既阐明了它们的结构，又提供了可能在星际介质中寻找的光谱“特征”，为这些物种的存在（或不存在）提供了证据。

Professor Robert J. McMahon, of the Department of Chemistry at the University of Wisconsin - Madison, is supported by the Organic and Macromolecular Chemistry Program for his studies directed toward the elucidation of the identity, structure, properties, and reactivity of organic molecules that occur in interstellar space. A combination of experimental and computational investigations are focused on organic species that are either known to or are likely to exist in the interstellar medium. These organic species will be generated in the laboratory, and their molecular structure investigated by infrared, ultraviolet/visible, electron spin resonance, and microwave spectrometry. In order to address the question of the existence of cyclic, aromatic species in interstellar space, as well as the mechanisms for their formation from acyclic molecules whose existence has been demonstrated, the fundamental chemical mechanisms by which open-chain organic molecules undergo ring closure will be investigated. Additional studies will attempt to detect aromatic species and their precursors in the interstellar medium through a combination of laboratory rotational spectroscopy and subsequent radio-astronomical searches.The origin of the so-called "diffuse interstellar bands" has been described as one of the fundamental problems in modern astronomy and molecular spectroscopy. At the present time, it is not known with certainty whether cyclic species displaying the unusual stabilization known as aromaticity exist in interstellar space and, if so, how these species can be formed from the acyclic molecules that are known to exist there. With the support of the Organic and Macromolecular Chemistry Program, Professor Robert J. McMahon, of the Department of Chemistry at the University of Wisconsin - Madison, is carrying out a combination of experimental and calculational studies designed to address these questions. By preparing acyclic precursors to aromatic species and examining their structure and reactivity, Professor McMahon explores the fundamental reaction chemistry which could occur in interstellar space. By probing these species with a variety of spectroscopic techniques, he both elucidates their structures and provides spectroscopic "signatures" which may be sought in the interstellar medium, providing evidence for the existence (or absence) of these species.