Laboratory and radio-astronomical spectroscopy of the hyperfine structure of N2D+

We present the first laboratory measurements of the hyperfine structure of the J = 1 <-- 0 rotational transition of N2D+, a good tracer of the dense regions of molecular cloud cores, and the spectra of unresolved high J transitions recorded in the 308-463 GHz region. Together with a high sensitivity radio-astronomical spectrum of the N2D+ J = 1 --> 0 rotational transition in a quiescent cloud core, we determined with high precision the frequencies of the seven hyperfine components and the molecular spectroscopic constants, allowing us to make predictions on the N2D+ frequencies of higher J transitions occurring in the submillimeter-wave region.