Production and Characterization of Ytterbium Monohydroxide (YbOH) for Next-Generation Parity and Time-Reversal Violating Physics Searches

Citation

Pilgram, Nickolas Hovanec (2023) Production and Characterization of Ytterbium Monohydroxide (YbOH) for Next-Generation Parity and Time-Reversal Violating Physics Searches. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/05m0-4g74. https://resolver.caltech.edu/CaltechTHESIS:08062022-012526440

Abstract

New sources of parity (P) and time-reversal (T) violating physics are motivated by several unanswered questions in fundamental physics, including the observed imbalance between matter and anti-matter in the universe. P,T-violating effects can induce permanent electric dipole moments (EDMs) in atoms and molecules, allowing them to act as sensitive probes of new physics. The linear, triatomic molecule ytterbium monohydroxide (YbOH) has emerged as a promising candidate for next-generation molecular EDM searches, because it possesses both an electronic structure amenable to optical cycling and parity doublets in the bending mode. These features enable laser cooling, highly polarizable science states, and internal comagnetometry which promises an order-of-magnitude improvement to current EDM sensitivities. Additionally, different isotoplogues of YbOH offer sensitivity to different sources of P,T-violating physics: leptonic sources via a measurement of the electron’s EDM in ¹⁷⁴YbOH and hadronic sources via a measurement of the nuclear magnetic quadrupole moment (NMQM) of the ¹⁷³Yb nucleus in ¹⁷³YbOH. In this dissertation, I describe the design, construction, and optimization of a YbOH cryogenic buffer gas beam (CBGB) source, including the implementation of laser-enhanced chemical reactions for increased molecular production. Direct and frequency modulated (FM) absorption spectroscopy and laser-induced fluorescence measurements (LIF) were implemented in the CBGB source, and LIF and separated field pump/probe microwave optical double resonance spectroscopy was conducted in a supersonic molecular beam source. Additionally, laser-enhanced chemical reactions were utilized to develop a novel spectroscopic technique critical to the observation of the spectrum of the odd isotopologues. FM absorption spectroscopy in the CBGB source allowed the observation of the previously unobserved, weak òΠ_1/2(1,0,0)-X̃²Σ⁺(3,0,0), [17.68], and [17.64] vibronic bands. The X̃²Σ⁺(0,0,0) ground state has been characterized at high precision and the òΠ_1/2(1,0,0)-X̃²Σ⁺(3,0,0) band of ¹⁷⁴YbOH and the òΠ_1/2(0,0,0)-X̃²Σ⁺(0,0,0) band of the odd ^171,173YbOH isotopologues have been characterized for the first time. This work provides much of the spectroscopic knowledge needed to implement next-generation P,T-violating physics searches in YbOH.

Thesis Files