Saturated-absorption cavity ring-down spectroscopy.

Area of Science:

• Molecular Spectroscopy
• Quantum Chemistry
• Laser Physics

Background:

• Cavity ring-down spectroscopy (CRDS) is a sensitive technique for measuring absorption.
• Determining molecular structures, especially hyperfine structures, requires high precision.
• Previous methods faced challenges in separating background signals from absorption.

Purpose of the Study:

• To introduce a novel CRDS approach enabling simultaneous background and signal retrieval.
• To apply this method for high-accuracy measurement of molecular hyperfine structures.
• To investigate the hyperfine structure of an excited vibrational state of 17O12C16O.

Main Methods:

• Developed a theoretical model to decouple empty-cavity background and absorption signals.
• Implemented CRDS with the sample gas in the saturated-absorption regime.
• Utilized high sensitivity and frequency precision for spectroscopic measurements.

Main Results:

• Successfully decoupled and retrieved both background and absorption signals.
• Achieved unprecedented accuracy (parts in 10{-11}) in spectroscopic measurements.
• Reported, for the first time, the hyperfine structure of an excited vibrational state of 17O12C16O.

Conclusions:

• The novel CRDS approach offers enhanced sensitivity and precision for spectroscopy.
• This technique provides a robust method for measuring complex molecular structures.
• The accurate determination of hyperfine structure advances molecular physics and chemistry.