High-Precision Spectroscopy of CH5+: Demystifying the Ro-Vibrational Spectrum

CH5 的高精度光谱分析：揭开 Ro 振动光谱的神秘面纱

• 批准号: 1213811
• 负责人: Benjamin McCall
• 金额: $ 46万
• 依托单位: University of Illinois at Urbana-Champaign
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-08-01 至 2016-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1213811&HistoricalAwards=false
• 关键词: Precision; Spectroscopy; CH5+; Demystifying; Ro

Benjamin McCall of the University of Illinois at Urbana-Champaig, is supported by an award from the Chemical Structure, Dynamics and Mechanisms program in the Chemistry division to implement two complementary experiments to study the high-resolution infrared spectrum of CH5+. This ion is the prototypical carbonium ion of the type so successfully used by George Olah and colleagues for superacid chemistry, and is also a critical intermediate in interstellar chemistry. A high-resolution ro-vibrational spectrum consisting of nearly 1000 lines was obtained over a decade ago, and remains completely unassigned. The first experiment aims to record the CH5+ spectrum at room temperature with sub-MHz precision and accuracy using cavity-enhanced velocity modulation spectroscopy, to enable the first experimental determination of ground-state energy level spacings using the method of four-line combination differences. Our second experiment aims to record the CH5+ spectrum using a novel fast ion beam spectrometer fed by a continuous supersonic expansion discharge source, to provide the first unambiguous, high-precision spectrum of CH5+ at low temperature; this in turn enables the experimental determination of the energies of the lowest rotational energy levels of CH5+. Taken together, these experiments should provide the first understanding of the ro-vibrational structure of this enigmatic molecule, and enable McCall and coworkers to construct an energy level diagram of the ground vibrational state of this ion for the first time. Ultimately, this new understanding should also enable the radio-astronomical detection of this important ion in dense interstellar clouds. This research, and associated activities, can be expected to have a broad impact in terms of enhancing interdisciplinary research, training undergraduate and graduate students, and integrating teaching and research. The overarching theme of these efforts is to bring together the chemistry, astronomy, and physics communities, and to encourage cross-fertilization between these three disciplines.

伊利诺伊大学Urbana-Champaig的本杰明·麦考尔（Benjamin McCall）得到了化学结构，动力学和机制计划的奖励，以实施两个补充实验，以研究CH5+的高分辨率红外光谱。 该离子是乔治·奥拉（George Olah）及其同事用于超酸化学的典型碳离子，也是星际化学中的关键中间体。 十年前，获得了由近1000条线组成的高分辨率RO振动光谱，并完全未分配。 第一个实验旨在使用腔体增强速度调制光谱谱图在室温下以亚MHz精度和准确性记录CH5+光谱，以便使用四线组合差异的方法对基地态能级间距进行首次实验确定。 我们的第二个实验旨在使用由连续超音速膨胀放电源喂食的新型快速离子束光谱仪记录CH5+光谱，以在低温下提供第一个明确的，高精度的CH5+频谱；反过来，这可以实验确定CH5+最低旋转能级的能量。综上所述，这些实验应首先了解该神秘分子的RO振动结构，并使McCall和同事首次构建该离子的地面振动状态的能级图。 最终，这种新的理解还应该使对这一重要离子在密集的星际云中的无线电习惯检测。 可以预期，这项研究和相关的活动在增强跨学科研究，培训本科生和研究生以及整合教学和研究方面会产生广泛的影响。 这些努力的总体主题是将化学，天文学和物理社区融合在一起，并鼓励这三个学科之间的跨施用。