Infrared laser spectrum of high J pure rotational transitions of 4HeD+

Many high J pure rotational lines of HeD+ in the mid-infrared region up to and above the asymptotic dissociation threshold have been detected in a D2/He ac glow discharge. Eighteen transitions belonging to the v=0 and v=1 levels were identified, including two bound-to-quasibound and one quasibound-to-quasibound transition. The highest quasibound level involved in the observed spectrum (v=0, J=34) is over 2000 cm−1 above the dissociation limit. A least-squares fit of the data to the rotational term expression of a linear 1Σ+ molecule yielded spectroscopic constants for HeD+ up to the distortion constant Nv.