High resolution spectral analysis of oxygen. II. Rotational spectra of a ~1Δ _g O _2 isotopologues

摘要

As part of a comprehensive review on molecular oxygen spectroscopy, we have measured rotational spectra of isotopic forms of molecular oxygen in its a ~1Δ _g electronic state with high-resolution terahertz spectroscopy. The data are recorded in close proximity to predicted positions. Due to the high resolution and good signal-to-noise ratio, the fundamental hyperfine parameters eQq and C _I are determinable for ~(17)O-substituted species for the first time. A refined nuclear spin orbit coupling constant, a -211.9328(283) MHz, was determined, and is roughly two orders of magnitude more precise than values determined from near infrared spectroscopy or electron spin resonance studies. Vibrationally excited oxygen in the a ~1Δ _g electronic state was also observable with small signal levels for many of the rotational transitions.