Accurate rest frequencies for the submillimetre-wave lines of the -containing isotopologues of and

Dipartimento di Chimica “G. Ciamician”, via F. Selmi 2, 40126 Bologna, Italy e-mail: [luca.dore;luca.bizzocchi;claudio.degliesposti;francesca.tinti4]@unibo.it

Received: 27 October 2008
Accepted: 13 January 2009

Abstract

The submillimetre-wave spectrum of the molecular ions N¹⁵NH⁺, ¹⁵NNH⁺, N¹⁵ND⁺, and ¹⁵NND⁺ have been investigated in the laboratory using a source-modulation microwave spectrometer equipped with a negative glow discharge cell. The diazenylium ion was produced in a Ar/N₂/H₂(D₂) discharge plasma and the ¹⁵N-containing isotopologues were observed in natural abundance. Six new rotational transitions for the protonated species and seven for the deuterated ones were accurately measured in the frequency range 270-760 GHz. These new laboratory measurements of the rare isotopologues of N₂H⁺ provide very precise rest frequencies at millimetre and submillimetre wavelengths useful for the radioastronomical identification of their rotational lines in the ISM.