Microwave and synchrotron far infrared spectroscopy of transient molecules

从星际云到遥远卫星的大气层，天文来源的分子组成非常有趣，因为它提供了对我们宇宙演化的见解。例如，在恒星之间的云层中已知有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组成部分。这些星际云最终形成了新的太阳系，它们的化学成分被望远镜跟踪，以检测单个分子吸收或发射光时的不同分子指纹。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。每年在远程来源中检测到几种新化合物，用于改进其化学演化模型，但明确识别新物种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光谱学的最新进展来解决这一需求，以非常详细地测量新型瞬态分子的最低能量状态，这些分子是天体化学过程的潜在成分。其中许多也是短寿命的物种，它们驱动着地球上的反应，包括燃烧、薄膜沉积和大气反应。除了表征新化合物的独特指纹外，还需要这些光谱来获得基本的分子性质，例如几何形状，内部重排的障碍以及旋转和振动运动之间相互作用的性质。这种精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新方法，用于生产和探测MW和FIR区域的瞬态物种的混合物。学员将在马尼托巴大学使用两台最先进的定制傅里叶变换微波（FTMW）光谱仪，以优化新型化合物的生成。一个提供快速MW光谱调查，以识别气体混合物的各个成分的旋转跃迁，而另一个使用谐振腔，然后非常精确和灵敏地记录特定的特征（一个接一个）。从光谱中提取的信息指导我们使用萨斯卡通的加拿大光源（CLS）同步加速器的FIR光束线对分子的振动指纹进行调查;世界上仅有的四个为此目的配备的设施之一。未来几年，我们将开发大数据自动分配策略来处理复杂的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开辟高分辨率光谱学领域。

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.