Precision Spectroscopy of Fullerenes: Towards Resolving Astrophysical Molecular Complexity

富勒烯-中空的对称碳笼-代表着天文环境中发现的最大的分子，并极大地改变了我们对太空中分子复杂性的理解。鉴于富勒烯C60、C70和C60+在天文天体中的普遍存在，预计还会有其他密切相关的富勒烯和富勒烯衍生物存在，但由于它们在实验室进行研究具有挑战性，无法获得天文鉴定所需的准确数据。利用新的实验室技术，这项研究项目将产生对富勒烯及其衍生物的长波红外光谱的高分辨率测量，这些光谱可能是天文探测的候选对象，并可能是在行星星云等天文物体中观察到的许多不明红外发射特征的原因。新获得的光谱将与大型红外望远镜的数据进行比较，目的是识别造成这些未知特征的分子。该项目将直接支持和培训一名研究生和一名博士后学者学习高级实验室天体物理方法，并为本科生提供研究机会。利用定制的高光谱分辨率、高灵敏度和宽带探测的腔增强频率梳光谱仪，研究小组将在6.5-10.5微米波长范围内测量富勒烯及其衍生物的振动分辨低温长波红外光谱。这些测量将成为大分子天文观测和量子计算的重要基准。研究系统将包括对称的富勒烯C70以及极性富勒烷C60H2和C59N，它们的成功测量将为研究更复杂的分子铺平道路，包括金属富勒烯(含金属富勒烯)和内富勒烯(包裹原子或分子的富勒烯)。该项目将利用强大的学术和产业合作伙伴关系，开发新的光源、高分辨率光谱仪和相机，以极大地提高精密红外光谱分析的潜力。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Fullerenes --- hollow, symmetric carbon cages --- represent the largest molecules identified in astronomical environments and have dramatically altered our understanding of molecular complexity in space. Given the prevalence of the fullerenes C60, C70, and C60+ in astronomical objects, other closely related fullerenes and fullerene derivatives are also expected to be present there, but because they are challenging to study in the laboratory, accurate data required for their astronomical identification are unavailable. Employing novel laboratory techniques, this research project will yield high-resolution measurements of the long-wave infrared (LWIR) spectra of fullerenes and their derivatives that are plausible candidates for astronomical detection and may be responsible for numerous unidentified infrared emission features observed in astronomical objects such as planetary nebulae. The newly acquired spectra will be compared with data from large infrared telescopes with the goal of identifying the molecules responsible for the unidentified features. This project will directly support and train a graduate student and a postdoctoral scholar in methods of advanced laboratory astrophysics, as well as provide research opportunities to undergraduate students.Using a custom-built cavity-enhanced frequency comb spectroscopy apparatus which combines high spectral resolution, high sensitivity, and broadband detection, the research team will measure rovibrationally resolved low-temperature LWIR spectra of fullerenes and fullerene derivatives in the 6.5-10.5 micrometer wavelength region. The measurements will serve as important benchmarks for astronomical observations and quantum calculations of large molecules. Systems for study will include the symmetric fullerene C70, as well as the polar fulleranes C60H2 and C59N, whose successful measurements will pave the way for investigations of yet more complex molecules including metallofullerenes (metal-bearing fullerenes) and endofullerenes (fullerenes encapsulating an atom or a molecule). This project will take advantage of strong academic-industrial partnerships to develop novel light sources, high-resolution spectrometers, and cameras with the potential to greatly advance precision infrared spectroscopy.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.