High Precision Energy Levels for the Simplest Polyatomic Molecule (H3+)

H3+是具有两个以上原子的最简单的分子：它由两个电子结合的三个质子组成。 因此，它是测试分子能级的最新理论计算的理想基准系统。H3+的重要性不仅在于这些基本原因，还在于它在各种天文环境中被广泛观察到，包括木星和土星的大气层以及恒星之间的气体云。 这些观测是通过精确确定分子发出的光的颜色来进行的，这种技术称为“光谱学”。 最新的计算可以重现H3+的颜色，达到目前实验室光谱测量的精度，因此理论发展的进一步进展将需要改进实验室仪器。 该研究小组计划利用一种新的仪器，使他们能够测量H3+颜色，精度比以前的工作高10,000倍。 由此产生的数据集将作为高级理论计算的持久基准，也将有助于对这种重要分子的天文观测。 从长远来看，预计这项工作将有助于开发控制化学反应的改进方法，从而推动工业部门的一个重要部分。这项工作将使用最近建造的仪器，允许常规的分子离子亚多普勒光谱。 这台仪器将升级到大约30千赫兹或百万分之一波数的精度，然后用于记录H3+在中红外的高精度光谱。 使用组合差异和有效的哈密顿拟合的分析将用于产生一组实验确定的H3+能级，其精度比以前的工作高出大约四个数量级。 这些精确的能级将允许直接测试对玻恩-奥本海默近似的非绝热修正，各种经验修正，并最终计算H3+的兰姆位移。

H3+ is the simplest molecule with more than two atoms: it consists of three protons bound by two electrons. As such, it is an ideal benchmark system for testing state-of-the-art theoretical calculations of molecular energy levels. H3+ is significant not only for these fundamental reasons, but also because it has been widely observed in a variety of astronomical environments, including the atmospheres of Jupiter and Saturn and in clouds of gas between stars. These observations are made by precisely determining the colors of light that are emitted by the molecule, a technique called "spectroscopy". The latest calculations can reproduce the colors of H3+ to within the accuracy of current laboratory spectroscopy measurements, so further progress in theoretical development will require improvements in the laboratory instrumentation. The group supported by this grant plans to utilize a novel instrument that will allow them to measure H3+ colors to a precision that is 10,000 times better than previous work. The resulting dataset will serve as an enduring benchmark for high-level theoretical calculations, and will also assist astronomical observations of this important molecule. In the long run, it is anticipated that this work will help in the development of improved methods of controlling chemical reactions and thereby advance a significant fraction of the industrial sector.The work will use a recently-constructed instrument that allows routine sub-Doppler spectroscopy of molecular ions. This instrument will be upgraded to achieve a precision of approximately 30 kiloHertz, or one-millionth of a wavenumber, and then used to record high-precision spectra of H3+ in the mid-infrared. An analysis using combination differences and effective Hamiltonian fitting will be used to produce a set of experimentally determined energy levels of H3+, with a precision that is approximately four orders of magnitude better than previous work. These precise energy levels will permit the direct testing of non-adiabatic corrections to the Born-Oppenheimer approximation, various empirical corrections, and ultimately calculations of the Lamb shift for H3+.