Stahl Pascal, Arenas Benjamin E, Domingos Sérgio R, Fuchs Guido W, Schnell Melanie, Giesen Thomas F
Institute of Physics, University of Kassel, Heinrich-Plett-Str. 40, 34132 Kassel, Germany.
Deutsches Elektronen-Synchrotron (DESY), Notkestr. 85, 22607 Hamburg, Germany and Institut für Physikalische Chemie, Christian-Albrechts-Universität zu Kiel, Max-Eyth-Str. 1, 24118 Kiel, Germany.
Phys Chem Chem Phys. 2020 Sep 30;22(37):21474-21487. doi: 10.1039/d0cp03523h.
The tracking of symmetry-breaking events in space is a long-lasting goal of astrochemists, aiming at an understanding of homochiral Earth chemistry. One current effort at this frontier aims at the detection of small chiral molecules in the interstellar medium. For that, high-resolution laboratory spectroscopy data is required, providing blueprints for the search and assignment of these molecules using radioastronomy. Here, we used chirped-pulse Fourier transform microwave and millimeter-wave spectroscopy and frequency modulation absorption spectroscopy to record and assign the rotational spectrum of the chiral aromatic molecule styrene oxide, C6H5C2H3O, a relevant candidate for future radioastronomy searches. Using experimental data from the 2-12, 75-110, 170-220, and 260-330 GHz regions, we performed a global spectral analysis, which was complemented by quantum chemistry calculations. A global fit of the ground state rotational spectrum was obtained, including rotational transitions from all four frequency regions. Primary rotational constants as well as quartic and sextic centrifugal distortion constants were determined. We also investigated vibrationally excited states of styrene oxide, and for the three lowest energy vibrational states, we determined rotational constants including centrifugal distortion corrections up to the sextic order. In addition, spectroscopic parameters for the singly-substituted 13C and 18O isotopologues were retrieved from the spectrum in natural abundance and used to determine the effective ground state structure of styrene oxide in the gas phase. The spectroscopic parameters and line lists of rotational transitions obtained here will assist future astrochemical studies of this class of chiral organic molecules.
追踪太空中的对称性破缺事件是天体化学家长期以来的目标，旨在理解地球上的同手性化学。目前在这一前沿领域的一项工作旨在探测星际介质中的小型手性分子。为此，需要高分辨率的实验室光谱数据，为利用射电天文学搜索和识别这些分子提供蓝本。在此，我们使用啁啾脉冲傅里叶变换微波和毫米波光谱以及频率调制吸收光谱来记录和识别手性芳香分子氧化苯乙烯（C6H5C2H3O）的转动光谱，它是未来射电天文学搜索的一个相关候选分子。利用来自2 - 12、75 - 110、170 - 220和260 - 330 GHz区域的实验数据，我们进行了全局光谱分析，并辅以量子化学计算。获得了基态转动光谱的全局拟合，包括来自所有四个频率区域的转动跃迁。确定了主要转动常数以及四次和六次离心畸变常数。我们还研究了氧化苯乙烯的振动激发态，对于三个最低能量的振动态，我们确定了转动常数，包括高达六次项的离心畸变修正。此外，从自然丰度的光谱中获取了单取代13C和18O同位素异构体的光谱参数，并用于确定气相中氧化苯乙烯的有效基态结构。此处获得的转动跃迁的光谱参数和谱线列表将有助于未来对这类手性有机分子的天体化学研究。
