Graduation Year


Document Type

Open Access Senior Thesis

Degree Name

Bachelor of Arts



Reader 1

Richard Mawhorter

Reader 2

Dwight Whitaker

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2023 Sean T Jackson


This main focus of this thesis is the use of molecular spectroscopy in the search for New Physics. Diatomic molecules offer interesting experimental opportunities in the search for physics beyond the Standard Model, including CP-violations due to the electric dipole mo- ment of the electron and other parity non-conservation effects. The work presented here concentrates mainly on the PbF molecule. Due to its large internal electric field, low sen- sitivity to external magnetic fields, and the presence of low-lying states of opposite parity in the 207PbF isotopolgue, PbF remains a compelling candidate for parity non-conservation studies. A robust global fit of all four naturally occurring isotopologues of PbF has now been completed, including 1331 lines of data across both the microwave and infrared bands. This global fit has a reduced mean square error of 0.567, meaning our data has fit far better than the expected error, which is especially true for the infrared lines. The correlated parameters AD and γ have been separated in this fit, and Born-Oppenheimer breakdown terms for the Y01 and p00 parameters have been determined. The global fit was also used to predict the first several energy levels of radioactive 205PbF, which appears to have similar low-lying states of opposite parity as 207PbF. Preliminary work on another interesting candidate molecule for aiding New Physics searches, YbO, is also presented here, including a new high-precision microwave measurement of the J=1-0 transition 176YbO.