Free Molecule Studies by Perturbed γ-γ Angular Correlation: A New Path to Accurate Nuclear Quadrupole Moments

Area of Science:

• Nuclear Physics
• Atomic and Molecular Physics
• Computational Chemistry

Background:

• Accurate nuclear quadrupole moments (Q) are vital for validating nuclear structure models.
• Interpreting nuclear quadrupole interactions requires precise Q values linked to electronic and molecular structures.

Purpose of the Study:

• To present a new method for determining nuclear quadrupole moments.
• To apply this method to Hg and Cd halides, yielding benchmark Q values.

Main Methods:

• Utilized perturbed gamma-gamma angular correlation measurements on free small linear molecules.
• Integrated these measurements with state-of-the-art ab initio electronic structure calculations of the electric field gradient.

Main Results:

• Determined the nuclear quadrupole moment for Mercury-199 (Q(^{199}Hg,5/2^{-})) to be +0.674(17) barn.
• Determined the nuclear quadrupole moment for Cadmium-111 (Q(^{111}Cd,5/2^{+})) to be +0.664(7) barn.

Conclusions:

• The combined experimental and computational approach offers a novel and effective route to accurate nuclear quadrupole moments.
• This methodology is applicable to a range of other nuclear and molecular systems.