Cavity-Ring-Down Spectroscopy on Water Vapor in the Range 555-604 nm

Area of Science:

• Atmospheric Chemistry
• Molecular Spectroscopy

Background:

• Accurate water vapor spectra are crucial for atmospheric modeling and remote sensing.
• Existing spectral databases may have limitations in coverage and accuracy.

Purpose of the Study:

• To record a high-resolution water vapor absorption spectrum in the visible range.
• To identify and assign previously unobserved spectral lines.
• To improve the accuracy of water vapor spectral data.

Main Methods:

• Pulsed cavity-ring-down spectroscopy (CRDS) was utilized.
• Measurements were performed in the 555-604 nm wavelength range.
• Spectral lines were calibrated against an iodine standard.

Main Results:

• A total of 1830 water vapor absorption lines were recorded with 0.01 cm(-1) accuracy.
• 800 lines were not found in the HITRAN 96 database.
• 243 lines were absent from a recent Fourier transform spectrum.
• 111 unobserved lines were assigned rovibrational quantum numbers using first-principles calculations.

Conclusions:

• The study provides a comprehensive and accurate water vapor absorption spectrum.
• Significant new spectral data were identified, expanding current databases.
• First-principles calculations aid in the assignment of complex molecular spectra.