Fourier transform far-infrared spectroscopy of HN2+ on the AILES beamline of synchrotron SOLEIL

Abstract

We report the pure rotation spectrum of HN2+ as measured by Fourier transform (FT) absorption spectroscopy in the 20–40 cm−1 spectral range. The cations are produced in a liquid nitrogen cooled hollow cathode discharge cell developed on the AILES beamline of synchrotron SOLEIL. The setup was optimized by recording rotation–vibration spectra of H3+ (with the ν2 band centered at about 2521 cm−1), HN2+ (with the ν1 band centered at about 3234 cm−1), and HCO+ (with the ν1 band centered at about 3089 cm−1). Many rotation–vibration lines have been assigned for each ion and five pure rotational transitions have been detected for HN2+. These results demonstrate the feasibility of recording far-infrared spectra of cationic species using FT broad band spectroscopy associated with the bright synchrotron radiation continuum as an alternative to laser-based frequency tunable techniques.