Saturation cavity ring-down spectrometry using a dynamical relaxation model.

Area of Science:

• Spectroscopy
• Atomic and Molecular Physics
• Quantum Optics

Background:

• Cavity Ring-Down Spectrometry (CRDS) is a sensitive technique for gas analysis.
• Saturation regime analysis in CRDS requires complex models.
• Doppler-free spectra are crucial for high-resolution gas measurements.

Purpose of the Study:

• To develop a simple approximate solution for the two-state rate equation model in CRDS.
• To enable baseline-immune spectral analysis in the adiabatic and low-saturation regimes.
• To accurately determine gas absorption coefficients and spectral line positions.

Main Methods:

• Application of a novel approximate solution to the two-state rate equation model.
• Analysis of decay signals in saturation cavity ring-down spectrometry.
• Recording a baseline-immune Lamb dip spectrum for methane.

Main Results:

• The proposed solution effectively analyzes decay signals in the specified regimes.
• Baseline-immune Doppler-free spectra for hyperfine transitions were obtained.
• Accurate linear absorption coefficients for gases in the saturation regime were determined.
• A precise line position for R1A2 transitions in methane's 2v2 + v3 band was measured at 6076.1084577(11) cm⁻¹.

Conclusions:

• The new approximate solution offers a simplified yet accurate approach to CRDS data analysis.
• This method enhances the capability to obtain high-precision spectroscopic data for gases.
• The demonstrated methane spectrum highlights the method's potential for fundamental molecular studies.