Infrared studies of large carbonaceous molecules.

大碳质分子的红外研究。

• 批准号: RGPIN-2020-06434
• 负责人: Peeters, Els
• 金额: $ 3.64万
• 依托单位: University of Western Ontario
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=763065
• 关键词: Infrared; studies; large; carbonaceous; molecules.

Polycyclic Aromatic Hydrocarbons (PAHs) are among the largest organic molecules found in space. They play a crucial role in various physical and chemical processes and in the prebiotic evolution toward life. Their infrared signature, the so-called Unidentified Infrared (UIR) emission bands, is omnipresent in our Galaxy and beyond. However, specifics of the emitting population remain elusive. Indeed, since the UIR bands originate from chemical bonds involving only nearest-neighbor atoms, they have only a weak dependence on the size and structure of the molecule, and it is therefore not possible to identify the individual PAH molecules that cause the infrared emission. Similarly, although it is firmly established that the PAH molecules are modified under the influence of the physical conditions of their environment (such as temperature, density, radiation field), the origin of these variations is not entirely understood. These unknowns are major roadblocks in i) understanding their connection with other cosmic organic species, ii) accurately quantifying their contribution to physical and chemical processes, and iii) the development of diagnostic tools that would transform the ubiquitous UIR bands into powerful probes of the physical and chemical conditions in the Universe. Today, the world is eagerly awaiting the launch of the James Webb Space Telescope (JWST). With its incredible improvement in spatial resolution, combined with its complete spectral coverage of the PAH infrared emission bands and superb sensitivity, JWST will revolutionize PAH research. Previous observations could only present spectra averaged over regions with vastly different properties, thus greatly confusing their interpretation. The amazing spatial resolution of JWST will disentangle these different regions. This will allow us to quantify precisely how PAHs are modified by the physical conditions of their host environment and thus trace how PAHs evolve across space. Because of its breakthrough potential for PAH research, I am leading a JWST program that will be among the first science observations done by JWST. The research program I propose will take full advantage of this unique opportunity to tackle key questions in PAH research. I will study how the infrared signature of PAHs changes on these fine spatial scales and how it is related to infrared signatures of other carbonaceous species. The observational data will be complemented by both a model of the physical and chemical evolution of PAHs and the NASA Ames PAH Infrared spectral database, which contains the physical and spectral properties of a large number of PAHs and related molecules. This combination allows to interpret the observational properties in terms of the composition of the PAH population and the mechanisms that are driving these changes.

多环芳烃（PAHs）是在太空中发现的最大的有机分子之一。它们在各种物理和化学过程中以及在生命前向生命进化中起着至关重要的作用。它们的红外特征，即所谓的未识别红外（UIR）发射带，在我们的银河系内外无处不在。然而，排放人口的具体情况仍然难以捉摸。事实上，由于UIR谱带源自仅涉及最近邻原子的化学键，因此它们对分子的大小和结构的依赖性很弱，因此不可能识别引起红外发射的单个PAH分子。类似地，尽管已经确定PAH分子在其环境的物理条件（如温度、密度、辐射场）的影响下发生了变化，但这些变化的起源并不完全清楚。这些未知数是主要的障碍，i）理解它们与其他宇宙有机物种的联系，ii）准确地量化它们对物理和化学过程的贡献，iii）开发诊断工具，将无处不在的UIR波段转化为宇宙物理和化学条件的强大探针。 今天，全世界都在热切地等待詹姆斯·韦伯太空望远镜（JWST）的发射。凭借其令人难以置信的空间分辨率的提高，结合其完整的光谱覆盖PAH红外发射波段和高超的灵敏度，JWST将彻底改变PAH的研究。以前的观测只能提供在性质差异很大的区域上平均的光谱，因此极大地混淆了它们的解释。JWST惊人的空间分辨率将解开这些不同的区域。这将使我们能够精确地量化多环芳烃如何被其宿主环境的物理条件所改变，从而追踪多环芳烃如何在空间中演变。由于其对PAH研究的突破性潜力，我正在领导一个JWST计划，该计划将成为JWST完成的第一批科学观察。我提出的研究计划将充分利用这一独特的机会，解决PAH研究中的关键问题。我将研究多环芳烃的红外特征如何在这些精细的空间尺度上变化，以及它如何与其他含碳物种的红外特征相关。观测数据将得到多环芳烃物理和化学演变模型和美国航天局艾姆斯多环芳烃红外光谱数据库的补充，该数据库载有大量多环芳烃和相关分子的物理和光谱特性。这种组合允许根据PAH人群的组成和驱动这些变化的机制来解释观察特性。