The rotational spectrum of trans-DCOOD: Lamb-dip measurements, THz spectroscopy and quantum-chemical calculations

► Rotational spectrum of trans-DCOOD recorded at sub-Doppler resolution: the Lamb-dip technique. ► The hyperfine structure due to the deuterium nuclei resolved and accurate hyperfine constants derived. ► High-level quantum-chemical calculations at the coupled-cluster level using large atomic-orbital basis sets of the hyperfine parameters: essential support to experiment. ► Doppler-limited measurements in the THz frequency domain.