Abstract Polyatomic molecules have been identified as sensitive probes of charge-parity violating and parity violating physics beyond the Standard Model (BSM). For example, many linear triatomic molecules are both laser-coolable and have parity doublets in the ground electronic state arising from the bending vibration, both features that can greatly aid BSM searches. Understanding the state is a crucial prerequisite to precision measurements with linear polyatomic molecules. Here, we characterize the fundamental bending vibration of YbOH using high-resolution optical spectroscopy on the nominally forbidden  transition at 588 nm. We assign 39 transitions originating from the lowest rotational levels of the state, and accurately model the state’s structure with an effective Hamiltonian using best-fit parameters. Additionally, we perform Stark and Zeeman spectroscopy on the state and fit the molecule-frame dipole moment to Dand the effective electrong-factor to . Further, we use an empirical model to explain observed anomalous line intensities in terms of interference from spin–orbit and vibronic perturbations in the excited state. Our work is an essential step toward searches for BSM physics in YbOH and other linear polyatomic molecules. 
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                            1D modeling of plasma streamers at ammonia-air flame conditions
                        
                    
    
            Abstract Self-consistent 1D modeling of streamers in ammonia-oxygen-nitrogen-water mixtures has been performed in this work. A fluid model that includes species transport, electrostatic potential, and detailed chemistry was developed and verified. This model is then used to simulate the avalanche, streamer formation and propagation phases, driven by a nanosecond voltage pulse, at different thermochemical conditions derived from a 1D laminar premixed ammonia-air flame. The applicability of the Meek’s criterion in predicting the streamer inception location was successfully confirmed. Streamer formation and propagation duration were found to vary significantly with different thermochemical conditions, due to the difference in ionization rates. The thermochemical state also affected the breakdown characteristics which was tested by maintaining the background reduced electric field constant. Detailed kinetic analyses revealed the importance of in the production of key radicals, such as O, OH, and NH2. Furthermore, the contributions of the dissociative electronic excitation of NH3towards the production of H and NH2radicals have also been reported. Spatial and temporal evolution of the electron energy loss fractions for various inelastic collision processes at different thermochemical states uncovered the input plasma energy spent of fuel dissociation and the large variability in the dominant processes during the avalanche and streamer propagation phases. The methodology and analyses reported in this work are key towards developing effective strategies for controlled nanosecond-pulsed non-equilibrium plasma sources used for ammonia ignition and flame stabilization. 
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                            - Award ID(s):
- 2002635
- PAR ID:
- 10548602
- Publisher / Repository:
- IOP Publishing
- Date Published:
- Journal Name:
- Journal of Physics D: Applied Physics
- Volume:
- 58
- Issue:
- 1
- ISSN:
- 0022-3727
- Format(s):
- Medium: X Size: Article No. 015204
- Size(s):
- Article No. 015204
- Sponsoring Org:
- National Science Foundation
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