Non-bonding molecular spinors and tests of fundamental physics with laser-cooled ions

• Applicant: Professor Dr. Robert Berger
• Subject Area: Theoretical Chemistry: Electronic Structure, Dynamics, Simulation
• Term: since 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 445296313

By definition, a non-bonding molecular orbital is an orbital, for which removal or addition of an electron does not change the chemical bond strength. At the same time, electrons on non-bonding molecular orbitals/spinors (NBMS) are of crucial importance for a wealth of physical applications, e.g., recent progress in direct laser cooling of molecules, including polyatomic ones, is essentially connected with understanding of the role of non-bonding spinors in the creation of closed cooling cycles, required for a molecule to be able to re-scatter thousands of photons. Laser-cooled molecules/ions can then be used for numerous other fundamental applications, such as the search for a permanent electron electric dipole moment and the measurement of the nuclear Schiff moment. Identification of molecules with desired properties (e.g. laser-coolability and sensitivity to nuclear Schiff moment) is challenging though, particularly it requires fundamental understanding of the peculiarities of the molecular electronic structure with electrons occupying NBMS. Despite the importance of NBMS, they have not been in the center of theoretical and experimental studies until recent years. We have defined previously certain classes of NBMS and identified subsequently molecules amenable for laser cooling possessing one or another type of NBMS. In this project we plan to undertake a systematic theoretical study of the particular role of NBMS in electronic structure of charged molecules. Special attention will be given on the one hand to the fundamental theory of NBMS and on the other hand to diverse applications such as laser cooling, search for exotic cosmic fields (including cold dark matter) and tests of QED effects in molecular ions. Laser-cooled molecular cations can be used subsequently in sympathetic cooling of other ions.

• DFG Programme: Research Grants
• International Connection: Russia
• Partner Organisation: Russian Science Foundation, until 3/2022
• Cooperation Partner: Dr. Timur Isaev, until 3/2022