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


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.


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 Ã2Π1/2(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 Ã2Π1/2(1,0,0)-X̃2Σ+(3,0,0) band of 174YbOH and the Ã2Π1/2(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.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:YbOH, Polyatomic, Spectroscopy, Electric Dipole Moment, Nuclear Magnetic Quadrupole Moment, Precision Measurement, Cryogenic Buffer Gas Beams
Degree Grantor:California Institute of Technology
Division:Physics, Mathematics and Astronomy
Major Option:Applied Physics
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Hutzler, Nicholas R.
Thesis Committee:
  • Endres, Manuel A. (chair)
  • Hutzler, Nicholas R.
  • Spiropulu, Maria
  • Filippone, Bradley W.
Defense Date:4 August 2022
Funding AgencyGrant Number
Heising-Simons Foundation2018-0681
Heising-Simons Foundation2019-1193
Heising-Simons Foundation2022-3361
NIST Precision Measurement Grant60NANB18D253
Record Number:CaltechTHESIS:08062022-012526440
Persistent URL:
Related URLs:
URLURL TypeDescription
https://10.1016/j.cplett.2018.11.030DOIAdapted for Ch. 4
https://10.1088/1367-2630/ab6eaeDOIPortions adapted for Ch. 5.1
https://10.1063/5.0055293DOIAdapted for Ch. 5.2-5.5
Pilgram, Nickolas Hovanec0000-0002-5467-3783
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:14995
Deposited By: Nickolas Pilgram
Deposited On:08 Aug 2022 23:58
Last Modified:20 Jun 2023 23:12

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