Unprecedented accuracy in molecular line-intensity ratios from frequency-based measurements.

ABSTRACT: Accurate determination of molecular transition intensities is vital to quantum chemistry and metrology, yet even simple diatomic molecules have historically been limited to 0.1% accuracy. Here, we show that frequency-domain measurements of relative intensity ratios outperform absolute methods, achieving 0.003% accuracy using dual-wavelength cavity mode dispersion spectroscopy. Enabled by high-precision frequency metrology, this approach reveals systematic discrepancies with state-of-the-art ab initio calculations, exposing subtle electron correlation effects in the dipole moment curve. Applied to line-intensity ratio thermometry (LRT), our technique determines gas temperatures with 0.5 millikelvin statistical uncertainty, exceeding previous LRT precision by two orders of magnitude. These r

SUBMITTER: Li JK 

PROVIDER: S-EPMC12442875 | biostudies-literature | 2025 Sep

REPOSITORIES: biostudies-literature