High-Resolution Spectroscopy of Heteronuclear Alkali Molecules: Structure and Dynamics

这个项目涉及小分子的研究以及它们如何与不同的原子相互作用。在一个实验中，激光被用来给分子提供精确定义的振动和旋转能量。这些分子在一个小房间里，然后与其他各种原子（氦、氩或钾）近距离接触（碰撞），这些原子也存在于房间里。第二束激光用来测定原子和分子之间的作用力如何影响分子的振动和旋转。在第二个实验中，激光被用来测量分子的能级和其他特性。这两个实验的结果将与基于量子力学理论的计算机模型进行比较，以测试对原子和分子如何相互作用的理解。这项提议的工作与其他当前感兴趣的领域的研究有关，例如量子计算和原子和分子的激光冷却。这也将有助于一些学生的高等教育。三到四名研究生将在此基础上撰写博士论文，大约六名本科生将在夏季通过利哈伊大学的REU（本科生研究经验）计划参与这些项目。将进行的具体活动包括NaCs和NaK三重态的反振动能级的测量，以及这些能级的精细和超精细结构的研究。目标是绘制势能曲线和跃迁偶极矩作为核间分离的函数，研究状态之间的自旋轨道和非绝热耦合，并使用能级模式来研究预解离和其他基本分子相互作用。在这样的一项努力中，得到支持的研究小组正在开发一种利用量子干涉效应来确定分子扰动的详细信息的技术。交互的NaCs 11（0+）和12（0+）状态被用作测试用例。该小组目前正在将他们的工作扩展到NaCs，因为它对冷却和捕获很感兴趣。该分子中较大的自旋轨道相互作用导致了强扰动和避免交叉，为实验和理论提供了有趣的新挑战。此外，该小组最近对碱分子的旋转非弹性碰撞的研究表明，在NaK分子与Ar或He原子的碰撞中，有强烈的J =偶数跃迁倾向。然而，在NaK与K原子的碰撞中没有观察到这种倾向。研究小组发现，在NaK与Ar或He的旋转非弹性碰撞中，取向在很大程度上保留了下来，但在与钾的碰撞中几乎完全被破坏了。该小组的理论计算开始为这些结果提供解释。最近的计算预测，在旋转非弹性碰撞中，方向或对准转移的概率有很强的J依赖性。进一步的实验将验证这些预测，并为分子碰撞理论提供严格的检验。

This project involves the study of small molecules and how they interact with different atoms. In one experiment, a laser is used to give the molecules a precisely defined amount of vibrational and rotational energy. The molecules, which are in a small chamber, then have close encounters (collisions) with various other atoms (helium, argon, or potassium) that are also present in the chamber. A second laser is used to determine how the forces between the atoms and the molecules affect the vibration and rotation of the molecules. In a second experiment, lasers are used to measure the energy levels and other properties of the molecules. The results of both experiments will be compared with computer models based on the theory of quantum mechanics in order to test the understanding of how atoms and molecules interact. The proposed work is relevant to research in other areas of current interest, such as quantum computing and laser cooling of atoms and molecules. It will also contribute to the advanced education of several students. Three or four graduate students will write Ph.D. dissertations based on this work, and approximately six undergraduate students will participate in these projects during the summers through Lehigh University's REU (Research Experiences for Undergraduates) program. The specific activities that will be carried out involve measurements of the ro-vibrational energy levels of triplet states of NaCs and NaK, and the investigation of fine and hyperfine structure of these levels. The goal is to map out potential energy curves and transition dipole moments as functions of internuclear separation, to study spin-orbit and non-adiabatic coupling between states, and to use patterns of energy levels to investigate predissociation and other fundamental molecular interactions. In one such effort, the supported research group is developing a technique using quantum interference effects to determine detailed information about molecular perturbations. The interacting NaCs 11(0+) and 12(0+) states are being used as the test case. The group is currently extending their work to NaCs, because it is of interest for cooling and trapping. The large spin-orbit interactions in this molecule, which lead to strong perturbations and avoided crossings, provide interesting new challenges for both experiment and theory. In addition, the group's recent studies of rotationally inelastic collisions of alkali molecules have revealed a strong propensity for Delta J = even transitions in collisions of NaK molecules with either Ar or He atoms. However, this propensity is not observed in collisions of NaK with K atoms. The group has found that orientation is largely preserved in rotationally inelastic collisions of NaK with Ar or He, but is almost completely destroyed in collisions with potassium. The group's theoretical calculations are beginning to provide explanations for these results. Recent calculations predict strong J dependences in the probabilities for transfer of either orientation or alignment in rotationally inelastic collisions. Further experiments will test many of these predictions and provide stringent tests of molecular collision theory.