NSF Award
2309361
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.<br/><br/><br/>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.<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.
