Significantly Improved Detection of Molecular Oxygen by Two-Color Resonance-Enhanced Multiphoton Ionization.

Area of Science:

• Atomic and Molecular Physics
• Spectroscopy
• Chemical Physics

Background:

• Accurate detection of molecular oxygen (O2) is crucial for various scientific disciplines.
• Existing spectroscopic methods for O2 lack sufficient sensitivity for certain applications.
• Fully rotationally resolved spectra are essential for detailed molecular analysis.

Purpose of the Study:

• To introduce a novel spectroscopic detection scheme for molecular oxygen.
• To enhance the sensitivity of O2 detection by approximately two orders of magnitude.
• To enable state-selective spectral analysis with high precision.

Main Methods:

• Utilizing two-color (2 + 1') resonance-enhanced multiphoton ionization (REMPI).
• Employing the 3d Rydberg complex for excitation.
• Achieving state-selective spectra without significant saturation or broadening.

Main Results:

• Demonstrated a sensitivity improvement of roughly two orders of magnitude over current methods.
• Obtained state-selective spectra comparable in signal intensity to established REMPI bands.
• Successfully observed weak 3dπ 1Δ2 ← X 3Σg- transitions in O2.

Conclusions:

• The new O2 spectroscopic detection scheme offers unprecedented sensitivity and state selectivity.
• This advancement facilitates the study of weak molecular transitions.
• The improved ionization efficiency and sensitivity will benefit numerous physical and chemical research areas.