LAUSR

Abstract We extended the measurements of the rotational transitions of D 2 H + up to 3 THz by using the JPL frequency multiplier chains and a TuFIR system at Toyama. D 2 H + was generated in an extended negative glow discharge cell cooled to liquid nitrogen temperature. We observed five new THz lines. All the available rotational transition frequencies together with the combination differences derived from the three fundamental bands were subject to least square analysis to determine the molecular constants. New THz measurements are definitely useful for better characterization of spectroscopic properties. The improved molecular constants provide better predictions of other unobserved rotational transitions.