NSF Award
2309340
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.<br/><br/>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.<br/><br/>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.
