Nuclear magnetization distribution effect in molecules: Ra⁺ and RaF hyperfine structure.

Area of Science:

• Atomic and Molecular Physics
• Nuclear Physics
• Quantum Chemistry

Background:

• Laser spectroscopy of radioactive RaF molecules is key for new physics searches.
• Radium nuclei's octupole deformation and parity-mixed levels are of significant interest.
• Accurate theoretical predictions are needed to aid experimental efforts.

Purpose of the Study:

• To develop a reliable theoretical method for predicting the hyperfine structure of RaF molecules.
• To account for the Bohr-Weisskopf (BW) effect, arising from finite nuclear magnetization distribution.
• To simplify the calculation of nuclear effects on molecular hyperfine structure.

Main Methods:

• Expressing the nuclear magnetization contribution using a single BW matrix element, independent of specific nuclear models.
• Extracting this parameter from existing electronic structure data of ions, atoms, or molecules.
• Applying the method to calculate the hyperfine structure contribution for 225Ra+ and 225RaF.

Main Results:

• A novel approach to calculate the Bohr-Weisskopf effect in RaF molecules was established.
• The nuclear magnetization distribution contribution to the hyperfine structure constant was quantified.
• For 225RaF, this contribution was found to be 4% for the ground state.

Conclusions:

• The proposed method simplifies the prediction of hyperfine structure in atoms and molecules.
• It allows for the separation of nuclear and electronic correlation problems.
• This approach enhances the accuracy of theoretical predictions for experiments searching for new physics.