Rotational and vibrational spectroscopy of 1-cyanoadamantane and 1-isocyanoadamantane

Abstract

Abstract Because of their high stability, the presence of diamond-type molecules has long been suspected in the interstellar medium, a hypothesis supported by the extraction of diamond nanocrystal from some meteorites. We report the rotational and vibrational investigation of two polar derivatives of adamantane (C10H16), 1-cyanoadamantane (C10H15–CN) and 1-isocyanoadamantane (C10H15–NC), using room temperature gas phase absorption spectroscopy. Pure rotational spectra have been recorded at millimeter wavelengths (75–220 GHz) while vibrational spectra were obtained in the far- and mid-infrared domains (50–3500 cm-1). Quantum chemical calculations have been performed on these two C 3 v rotors to support the spectral analysis enabling the assignment, for both species, of more than 7000 pure rotational transitions in the ground (A1 symmetry) and first vibrationally excited (E symmetry) states, and of most of the infrared active bands. The pure rotational lines were fit to their experimental accuracy using a symmetric-top Hamiltonian. Our study provides all necessary information for an active search of these species in space.