Microwave and synchrotron far infrared spectroscopy of transient molecules

从星际云到遥远卫星的大气，天文来源的分子组成是非常有趣的，因为它提供了对我们宇宙演化的见解。例如，在恒星之间的云中，已知有180多种分子，包括醇、醛和酮等有机化合物；其中一些被认为是益生元的基石。这些星际云最终形成了新的太阳系，当单个分子吸收或发射光时，它们的化学成分可以用望远镜来探测不同的分子指纹。这些独特的特征通常涉及分子旋转的变化，并发生在微波（MW）到远红外（FIR）波长。每年在偏远来源检测几种新化合物用于改进其化学演化模型，但新物种的明确鉴定需要基于实验室的光谱进行比较。***我的研究计划利用MW和FIR光谱的最新进展来解决这一需求，详细测量作为天体化学过程潜在组成部分的新型瞬态分子的最低能量状态。其中许多也是短命的物种，它们驱动地球上的反应，包括那些涉及燃烧、薄膜沉积和大气反应的反应。除了表征新化合物的独特指纹图谱外，还需要这些光谱来推导基本的分子性质，如几何形状、内部重排障碍以及旋转和振动运动之间相互作用的性质。这种准确的分子水平信息进一步加深了我们对瞬态化合物化学的理解，并将导致更好的模型和控制所有类型的化学过程。***这项研究的关键要素包括正在开发的在MW和FIR区域生产和探测瞬态物种混合物的新方法。学员将使用马尼托巴大学的两台最先进的定制傅立叶变换微波（FTMW）光谱仪来优化新化合物的生成。一种提供快速的毫瓦光谱测量，以识别气体混合物中单个组分的旋转跃迁，而另一种使用谐振腔，然后非常精确和灵敏地记录特定特征（一个接一个）。利用萨斯卡通加拿大光源（CLS）同步加速器的FIR光束线，从光谱中提取的信息指导我们对分子振动指纹的研究；这是世界上仅有的四个设施之一。在未来几年，我们开发的“大数据”自动化分配策略将处理复杂的MW和FIR光谱，这将为新的研究人员和越来越具有挑战性的科学问题打开高分辨率光谱领域。*** *** *** *** *** *** **

The molecular composition of astronomical sources, from interstellar clouds to the atmospheres of remote moons, is of great interest as it provides insights into the evolution of our Universe. For example, more than 180 molecules are known in clouds between stars including organic compounds such as alcohols, aldehydes and ketones; some of which are thought to be prebiotic building blocks. These interstellar clouds ultimately form new solar systems and their chemical composition is tracked using telescopes to detect distinct molecular fingerprints as individual molecules absorb or emit light. These unique features most often involve changes in molecular rotation and occur at microwave (MW) through far infrared (FIR) wavelengths. Detection of several new compounds in remote sources each year is used to refine models of their chemical evolution but the unambiguous identification of novel species requires laboratory-based spectra for comparison.***My research program addresses this need using the latest advances in both MW and FIR spectroscopy to measure, in great detail, the lowest energy states of novel transient molecules that are potential components of astrochemical processes. Many of these are also short-lived species that drive reactions on Earth including those involved in combustion, thin film deposition and atmospheric reactions. In addition to characterizing unique fingerprints of new compounds, these spectra are needed to derive fundamental molecular properties such as the geometry, barriers to internal re-arrangements and the nature of interactions between rotational and vibrational motions. This accurate molecular-level information furthers our understanding of the chemistry of transient compounds and will lead to better models and control of chemical processes of all types. ***Key elements of this research include the ongoing development of new methods for producing and probing mixtures of transient species in the MW and FIR regions. Trainees will use two state-of-the-art custom-built Fourier transform microwave (FTMW) spectrometers at the University of Manitoba to optimize the generation of novel compounds. One provides fast MW spectral surveys to identify rotational transitions of individual components of a gaseous mixture while the other uses a resonator cavity to then record specific features (one by one) very precisely and sensitively. Information extracted from the spectra guides our investigation of vibrational fingerprints of molecules using the FIR beamline of the Canadian Light Source (CLS) synchrotron in Saskatoon; one of only four facilities in the world equipped for this purpose. Our development of ‘big data' automated assignment strategies to deal with complex MW and FIR spectra over the next few years will open the field of high resolution spectroscopy to new researchers and increasingly challenging scientific questions. *** *** *** *** *** *** **