PM: Cold Radioactive Molecules for Precision Measurements.

宇宙是由物质组成的，但不包含反物质，这一事实是一个谜。没有人知道是哪个物理过程导致了早期宇宙中物质的产生，但我们知道它可以以一些不寻常的方式表现出来。一种方法是修改原子核的电磁特性，这可以在桌面上使用激光控制的原子和分子进行精确的研究。一些原子核比其他原子核对这些效应更敏感，几十年来，人们一直知道，在元素周期表的最后一行含有某些重的、不稳定的原子核的极性分子，与目前最先进的实验相比，将这种新物理的影响放大了大约一百万倍。然而，这些成果仍然没有实现；即使是最简单的分子的复杂性，再加上可以在实验室获得和处理的有限数量的不稳定核，使得这项研究非常具有挑战性。事实上，第一次基于激光对任何放射性分子进行精确测量是在几年前首次进行的。在这项研究中，PI将带领一组学生开发和演示一种新的方法来合成、冷却和精确研究含Re的分子的结构和性质--Re是对新的基础物理最敏感的核之一。研究小组将结合激光驱动的化学反应、低温氦气体冷却和精密光谱分析的新方法来研究含Re的多原子分子，这些分子的化学结构被调整，以使先进的量子控制能够研究这些奇异的原子核。此外，该方法将广泛适用于核结构、放射化学和核天体物理研究中含有不稳定核或稀有核的分子。含有重的、八极变形的核的分子，如镭，可以极大地增强强子CP破坏。与使用球形原子核的最先进的实验相比，分子间电磁环境和原子核的形状变形相结合，导致对违反CP的核Schiff矩的敏感度提高了约100万倍。此外，许多含Re的分子预计是可激光冷却的，这意味着它们为高灵敏度测量提供了一条先进的量子控制途径。然而，与这些物种合作的困难扼杀了他们的研究；事实上，直到最近几年，才对任何短暂的放射性分子物种进行了精确光谱分析。这项研究计划的目标是通过结合激光驱动的化学合成、低温缓冲气体冷却以及使用非常少量的材料来同时进行宽带和窄带光谱的新方法来合成、冷却和光谱研究包括RaOH在内的含Ar的多原子分子。该方法将在静态缓冲气体室中产生旋转和平移冷却到4K左右的分子，从而将它们置于光谱、激光冷却和精确测量的起点。此外，这些方法将是非常通用的，可以应用于各种含有外来核的分子或以其他方式仅在微量中可用的分子。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。

The fact that the Universe is made from matter, yet contains no anti-matter, is a mystery. Nobody knows which physical process was responsible for generation of matter in the early Universe, but we do know that it can manifest itself in some unusual ways. One way is by modifying the electromagnetic properties of nuclei, which can be studied precisely in a table-top setting using laser-controlled and atoms and molecules. Some nuclei are more sensitive than others to these effects, and it has been known for decades that polar molecules containing certain heavy, unstable nuclei in the last row of the periodic table amplify the effects of this new physics by around a million times compared to current state-of-the-art experiments. However, these gains remain unrealized; the complexity of even the simplest molecule, combined with the limited amounts of unstable nuclei which can be obtained and handled in the laboratory, made this research very challenging. Indeed, the first precise laser-based measurement of any radioactive molecule was first performed a few years ago. For this present study, the PI will lead a team of students to develop and demonstrate a new method to synthesize, cool, and precisely study the structure and properties of molecules containing radium – one of the nuclei with the highest sensitivity to new fundamental physics. The research team will combine laser-driven chemical reactions, cryogenic helium gas cooling, and new approaches to precision spectroscopy to study polyatomic radium-containing molecules, whose chemical structures are tuned to enable advanced quantum control to study these exotic nuclei. Furthermore, the method will be widely applicable to molecules containing unstable or rare nuclei for studies in nuclear structure, radiochemistry, and nuclear astrophysics.Molecules containing heavy, octupole-deformed nuclei, such as radium, offer extreme enhancement of hadronic CP-violation. The combination of the intermolecular electromagnetic environment and the shape deformation of the nucleus result in around a million-fold enhancement in sensitivity to CP-violating nuclear Schiff moments compared to state-of-the-art experiments using atoms with spherical nuclei. Furthermore, many radium-containing molecules are predicted to be laser-coolable, meaning that they offer an avenue to advanced quantum control for highly sensitive measurements. However, the difficulty of working with these species has stifled their study; indeed, only in the last few years has precision spectroscopy been performed on any short-lived radioactive molecular species. The goal of this research program is to synthesize, cool, and spectroscopically study radium-containing polyatomic molecules, including RaOH, by combining laser-driven chemical synthesis, cryogenic buffer gas cooling, and new approaches to both broadband and narrowband spectroscopy with very small quantities of material. The method will produce molecules which are rotationally and translationally cooled to around 4 K in a static buffer gas cell, thereby placing them at a starting point for spectroscopy, laser cooling, and precision measurements. Furthermore, the methods will be very general, and can be applied to a wide variety of molecules containing exotic nuclei or otherwise available only in trace amounts.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.