The hyperfine structure in the rotational spectra of D₂O: Lamb-dip measurements and quantum-chemical calculations

Abstract

Thirteen rotational transitions of the doubly deuterated isotopic species of water, D₂ ¹⁶O, have been recorded in the millimeter- and submillimeter-wave region. The Lamb-dip technique has been used to resolve the hyperfine structure due to deuterium quadrupole coupling, due to spin–rotation as well as dipolar spin–spin interactions, thus enabling the determination of the corresponding hyperfine parameters to a good accuracy. The experimental investigation has been assisted by high-level quantum-chemical calculations of the hyperfine parameters.

Keywords:

• D₂O
• rotational spectrum
• hyperfine structure
• Lamb-dip spectroscopy
• quantum-chemical calculations

Acknowledgements

This work has been supported by ‘PRIN 2007’ funds (project ‘Trasferimenti di energia, carica e molecole in sistemi complessi’) and by University of Bologna (RFO funds) as well as in Mainz by the Deutsche Forschungsgemeinschaft and the Fonds der Chemischen Industrie.

Notes

Note

1. It should be noted that the small bump shown in Figure 1 at approximately 403,562.1 MHz is due to poor baseline (accidentally resembling a very weak dip) and does not correspond to any spectral feature.