Rotational level spacings in HD from vibrational saturation spectroscopy

Abstract

The R(1), R(3) and P(3) ro-vibrational transitions in the (2-0) overtone band of the HD molecule are measured in Doppler-free saturation using the technique of NICE-OHMS spectroscopy. For the P(3) line, hitherto not observed in saturation, we report a frequency of $203821936805(60)$ kHz. The dispersive line shapes observed in the three spectra show strong correlations, allowing for extraction of accurate information on rotational level spacings. This leads to level spacings of ${\Delta }_{(J=3)-(J=1)}=13283245098(30)$ kHz in the $v=0$ ground state, and ${\Delta }_{(J=4)-(J=2)}=16882368179(20)$ kHz in the $v=2$ excited vibration in HD. These results show that experimental values for the rotational spacings are consistently larger than those obtained with advanced ab initio theoretical calculations at 1.5$\sigma$, where the uncertainty is determined by theory. The same holds for the vibrational transitions where systematic deviations of 1.7-1.9$\sigma$ are consistently found for the five lines accurately measured in the (2-0) band.

8 pages, 5 figures, Physical Review A, accepted

References in corpus (5)

• Benchmarking theory with an improved measurement of the ionization and dissociation energies of H${}_2$
• Constraints on extra dimensions from precision molecular spectroscopy
• Complete ${\alpha }^{6}m$ corrections to the ground state of H${}_2$
• Lamb-dips and Lamb-peaks in the saturation spectrum of HD
• Improved Ionization and Dissociation Energies of the Deuterium Molecule

Cited by in corpus (2)

• Leading-order QED effects in the ground electronic state of molecular hydrogen
• A Stimulated Raman Loss spectrometer for metrological studies of quadrupole lines of hydrogen isotopologues