Rovibrational Energies of ¹³C¹⁶O₂ Determined with Kilohertz Accuracy

Area of Science:

• Atmospheric Chemistry
• Molecular Spectroscopy
• Isotope Analysis

Background:

• Accurate spectroscopic data for carbon dioxide (CO2) are crucial for applications like carbon monitoring.
• The second most abundant isotopologue, 13C16O2, requires precise spectral characterization for advanced studies.

Purpose of the Study:

• To present high-accuracy spectroscopic data for 13C16O2 in the 1.6 μm region.
• To determine ground-state rotational energies and provide hybrid line positions for 13C16O2 transitions.
• To assess the perturbation status of specific vibrational states for improved modeling.

Main Methods:

• Comb-locked cavity ring-down saturation spectroscopy was employed.
• Analysis of combination differences was used to derive ground-state rotational energies.
• Rotational and centrifugal constants were fitted to vibrational state data.

Main Results:

• Positions of 88 spectral lines in three vibrational bands (30011e/30012e/30013e-00001e) were determined with kHz accuracy.
• First-time kHz-accuracy ground-state rotational energies were obtained.
• Hybrid line positions for 150 13C16O2 transitions were provided, with the 30013e state found to be unperturbed.

Conclusions:

• The precise isotopic line positions will enhance the Hamiltonian model for CO2.
• This data will improve quantitative remote sensing of carbon dioxide.
• The findings will facilitate tracking of carbon sources and sinks via isotopic analysis.