Molecular Spectroscopy to Measure Lifetimes and Collisional Dynamics of Lithium and NaK Molecules

用于测量锂和 NaK 分子的寿命和碰撞动力学的分子光谱

• 批准号: 2309340
• 负责人: Burcin Bayram
• 金额: $ 28.98万
• 依托单位: Miami University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-09-01 至 2026-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2309340&HistoricalAwards=false
• 关键词: Molecular; Spectroscopy; Measure; Lifetimes; Collisional

Scientists have developed remarkable methods to study the formation of molecules in interstellar medium although they are light years away from the Earth-based labs. They have also learned to generate ultracold molecules to explore their unique quantum properties. The research team will use a highly effective method known as a high-resolution molecular spectroscopy along with pulsed lasers to investigate the radiative properties of target diatomic (2-atom) molecules, lithium and NaK (a mixture of sodium and potassium), in a heatpipe oven. In the heatpipe oven some atoms chemically bind to form molecules. When exposed to laser light, molecules absorb photons from the laser and undergo a transition to their excited quantum state. The excited molecules eventually return to lower quantum states by emitting photons in a characteristic time scale, which is called the radiative lifetime. The decay time of the emitted photons can be probed using various time-resolved spectroscopic techniques. The research team will use a sophisticated photon-counting technique to record arrival time of the individual photon from a specific excited state. As the process repeats, the recorded number of photons builds up and the result yields molecular lifetime. Additionally, the research team will investigate the effect of the atomic and molecular collisions on lifetimes as collisions often alter the interaction of light with molecules. The primary potential benefit of this research is to gain knowledge of the fundamental understanding of radiative processes in molecules as they, for example, occur in the interstellar medium and in ultracold atomic and molecular physics. The project will also provide benchmark values to test the reliability of recent theoretical lifetime calculations and advance the understanding of how atoms and molecules interact. The broader impacts of the project are benefits to society by providing extensive hands-on research training for undergraduate and graduate students, and developing research-based educational materials for curriculum enrichment. Students will gain valuable knowledge and skills in atomic and molecular physics, and in advanced spectroscopic and optical techniques. During the science outreach program, the research team will engage with hundreds of K-12 students and their teachers, demonstrating the principles of light and optics to promote public understanding and appreciation of science.The goal of the project is to study the radiative lifetimes and collisional dynamics of highly excited lithium and NaK molecules. Molecular transitions are much more complex compared to the atomic transitions since each molecular quantum state consists of additional vibrational and rotational quantum levels. Thus, a high spectral resolution is needed to identify the correct transition pathway. The research team will use very precisely pulsed lasers to initiate the excitation process and a high-resolution molecular spectroscopy along with a photon-counting technique to detect photons from a specific vibrational-rotational quantum level. Such study can be used to detect predissociation, which is a process by which a chemical bond within the molecule is broken, and radiative association, which is the formation of a new molecule from colliding atoms. Thus, the measurements open up possibilities for searching predissociation and radiative association processes that are particularly important in interstellar clouds, plasma physics and meteorology. The study of highly excited lithium molecules is specifically interesting due to the exotic double peak structure in molecular states, opening up potential applications in ultracold physics. The output of this research program will be complementary to the recently calculated radiative lifetimes and will advance understanding of molecular interaction dynamics. The relatively simple yet still sufficiently rich internal structure of lithium and NaK molecules is then a compelling target for testing fundamental laws of nature and probing novel states of quantum matter.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.

科学家开发了出色的方法来研究星际培养基中分子的形成，尽管它们距离基于地球的实验室已经光明了几年。 他们还学会了生成超冷分子以探索其独特的量子特性。研究团队将使用一种高效的方法，称为高分辨率分子光谱以及脉冲激光器来研究靶性双原子（2个原子）分子，锂和Nak（钠和钾的混合物）的辐射特性，在热水烤箱中。在热管烤箱中，一些化学结合以形成分子。 当暴露于激光时，分子会从激光器中吸收光子，并经历其激发量子态的过渡。激发分子最终通过以特征性时间尺度发射光子来返回到较低的量子状态，这称为辐射寿命。可以使用各种时间分辨光谱技术探测发射光子的衰减时间。研究团队将使用精致的光子计数技术从特定的激发状态记录单个光子的到达时间。随着过程的重复，记录的光子数量累积，结果产生了分子寿命。此外，研究小组将研究原子和分子碰撞对寿命的影响，因为碰撞通常会改变光与分子的相互作用。这项研究的主要潜在优势是了解分子中对辐射过程的基本理解，例如，它们发生在星际培养基和超电原子和分子物理学中。该项目还将提供基准值，以测试最近理论寿命计算的可靠性，并提高对原子和分子相互作用的理解。该项目的更广泛影响是通过为本科和研究生提供广泛的动手研究培训，并开发基于研究的教育材料以进行课程丰富，从而对社会产生了更大的好处。 学生将获得原子和分子物理学以及高级光谱和光学技术的宝贵知识和技能。在科学宣传计划中，研究团队将与数百名K-12学生及其老师互动，展示光和光学的原理，以促进公众对科学的理解和欣赏。与原子过渡相比，分子过渡要复杂得多，因为每个分子量子态都由额外的振动和旋转量子水平组成。因此，需要高光谱分辨率来识别正确的过渡途径。研究团队将使用非常精确的脉冲激光器来启动激发过程和高分辨率分子光谱以及光子计数技术，以从特定的振动旋转量子水平检测光子。此类研究可用于检测预分离，这是分子中的化学键被破坏的过程，而辐射缔合是从碰撞原子中形成新分子的过程。因此，测量结果为搜索预分离和辐射关联过程开辟了可能性，这些过程在星际云，等离子体物理学和气象学中尤为重要。由于分子状态的外来双峰结构，对高度激发的锂分子的研究特别有趣，从而开放了超低物理中的潜在应用。该研究计划的输出将与最近计算出的辐射寿命互补，并将提高对分子相互作用动力学的理解。然后，相对简单但仍然足够丰富的锂和NAK分子的内部结构是测试自然界基本定律并探测量子问题的新状态的引人注目的目标。该奖项反映了NSF的法定任务，并被视为值得通过基金会的知识分子和更广泛影响的评估来审查审查标准来通过评估来获得支持。