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Updated: Jun 13, 2025

Measurement of Ultrafast Vibrational Coherences in Polyatomic Radical Cations with Strong-Field Adiabatic Ionization
Published on: August 6, 2018
2500 vibronic eigenstates of the NO3 radical
Henrik R Larsson1, Alexandra Viel2
1Department of Chemistry and Biochemistry, University of California, Merced, CA 95343, USA. NO3a[at]larsson-research.δe.
Researchers studied the vibronic structure of the nitrate radical (NO3) using advanced computational methods. They computed over 2500 states, revealing significant discrepancies with experimental data and highlighting the limitations of the Born-Oppenheimer approximation.
Area of Science:
- Atmospheric Chemistry
- Quantum Chemistry
- Spectroscopy
Background:
- The nitrate radical (NO3) is crucial in atmospheric chemistry.
- Its coupled and anharmonic vibronic structure is not fully understood.
- Accurate theoretical models are needed to interpret experimental spectra.
Purpose of the Study:
- To accurately compute the full-dimensional vibronic spectrum of the nitrate radical (NO3).
- To investigate the coupled and anharmonic vibronic structure of NO3.
- To assess the validity of the Born-Oppenheimer approximation for NO3.
Main Methods:
- Development and application of an accurate, coupled full-dimensional diabatic potential energy surface.
- Utilizing advanced tensor network state (TNS) methods for computation.
- Calculation of over 2500 vibronic states for the NO3 molecule.
Main Results:
- Computed vibronic spectrum shows good agreement with some experimental data, but significant disagreements for other levels.
- Observed large, symmetry-induced level splittings in the antisymmetric bending motion.
- Demonstrated substantial errors introduced by the Born-Oppenheimer approximation.
Conclusions:
- The study provides a significantly expanded computational dataset for NO3 vibronic states.
- Non-adiabatic effects are non-negligible and impact the accuracy of spectral predictions.
- The Born-Oppenheimer approximation is inadequate for describing the complex vibronic structure of NO3.
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