2023/03/31 by Frank M. J. Cozijn, Cozijn, F. M. J., M. L. Diouf +3 · 3 citations
Chemistry · Earth and Planetary Sciences · Engineering · #Atmospheric Ozone and Climate #Atomic Physics (physics.atom-ph) #FOS: Physical sciences #Laser Design and Applications #Spectroscopy and Laser Applications
paper · pdf · doi:10.48550/arxiv.2303.17818
openalex publication_date 2023/03/31 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The saturated absorption spectrum of the hyperfine-less S(0) quadrupole line in the (2-0) band of H2 is measured at λ=1189 nm, using the NICE-OHMS technique under cryogenic conditions (72~K). It is for the first time that a Lamb dip of a molecular quadrupole transition is recorded. At low (150-200 W) saturation powers a single narrow Lamb dip is observed, ruling out an underlying recoil doublet of 140 kHz. Studies of Doppler-detuned resonances show that the red-shifted recoil component can be made visible for low pressures and powers, and prove that the narrow Lamb dip must be interpreted as the blue recoil component. A transition frequency of 252 016 361 164 (8) kHz is extracted, which is off by -2.6 (1.6) MHz from molecular quantum electrodynamical calculations therewith providing a challenge to theory.