Rotational spectroscopy with an optical centrifuge.

Area of Science:

• Molecular spectroscopy
• Quantum mechanics
• Chemical physics

Background:

• Studying electronic transitions in molecules is crucial for understanding chemical reactions and material properties.
• Traditional spectroscopic methods are limited in their ability to probe molecules with high angular momentum.
• Oxygen molecules ((16)O2) serve as a model system for investigating fundamental molecular dynamics.

Purpose of the Study:

• To develop and demonstrate a new spectroscopic method for studying electronic transitions in molecules across a broad range of angular momentum.
• To enable the investigation of ro-vibrational transitions in oxygen molecules beyond thermally accessible rotational quantum numbers.
• To interpret the complex rotational spectra of the C(3)Πg electronic state in oxygen.

Main Methods:

• Employing an optical centrifuge to generate narrow rotational wave packets in the ground electronic state of (16)O2.
• Utilizing resonance-enhanced multi-photon ionization (REMPI) spectroscopy.
• Recording and analyzing ro-vibrational transitions between the X(3)Σg(-) and C(3)Πg electronic states.

Main Results:

• Demonstration of a novel spectroscopic technique capable of probing molecules with high angular momentum (N ≳ 120).
• Successful recording of multiple ro-vibrational transitions in oxygen, revealing complex spectral structures.
• Interpretation of the C(3)Πg electronic state's rotational spectra beyond conventional thermal limits.

Conclusions:

• The developed spectroscopic method provides unprecedented control over molecular rotation, extending the accessible range of angular momentum.
• This technique significantly advances the study of electronic transitions in molecules, particularly for complex systems.
• The findings offer new insights into the dynamics and spectroscopy of oxygen and other molecules.