Linear Probing of Molecules at Micrometric Distances from a Surface with Sub-Doppler Frequency Resolution

Area of Science:

• Molecular Spectroscopy
• Quantum Cascade Laser Applications
• Surface Science

Background:

• Precision spectroscopy is crucial for understanding molecular behavior and interactions.
• Studying molecules confined at subwavelength scales presents unique challenges and opportunities.
• Existing methods may lack the resolution or sensitivity for detailed molecule-surface interaction studies.

Purpose of the Study:

• To demonstrate a novel precision spectroscopy technique for subwavelength confined molecular gases.
• To investigate molecule-surface interactions using rovibrational selective reflection.
• To obtain new spectroscopic data for the SF6 greenhouse gas.

Main Methods:

• Utilizing a quantum cascade laser emitting at approximately 10.6 μm.
• Employing rovibrational selective reflection to probe NH3 and SF6 molecules.
• Achieving submegahertz resolution for measurements at micrometric distances (≈λ/2π) from a cell window.

Main Results:

• Successfully performed precision spectroscopy on confined NH3 and SF6 gases.
• Probed molecular interactions at distances of ≈λ/2π from the cell window.
• Obtained high-resolution spectroscopic data for SF6, valuable for molecular databases.

Conclusions:

• The developed technique enables molecule-surface interaction spectroscopy with high resolution.
• The method provides novel spectroscopic insights into the SF6 greenhouse gas.
• Future applications include compact frequency references and enhanced Casimir-Polder interaction measurements.