Detection of the Millimeter Wave Spectrum of Hydrogen Isocyanide, HNC^1,2

Abstract

The rotational spectra of three isotopic species of HNC have been observed in the millimeter wave region. In the case of the parent species, H 14 N 12 C, our measurement of the J = 1←0 transition unequivocally confirms the assignment of the U90.7 interstellar line to HNC. For the parent species the molecular constants obtained are B 0 = 45332.005(40) MHz and D 0 = 0.1019(50) MHz. Structural parameters derived from the ground state rotational constants of this linear molecule are r(H-N) = 0.987 (3) Å and r(N-C) =1.171 (4) Å.