The ν3 fundamental bands of HN+2, DN+2, and DCO+

Abstract

The ν3 (N–N or C–O stretch) fundamental bands of HN+2,DN+2, and DCO+ in the 5 μm region have been studied using a tunable infrared diode laser source. The absorption cell was a large liquid-nitrogen-cooled hollow cathode, and a discharge modulation scheme was used to enhance sensitivity and discriminate in favor of molecular ions. We observed 22 transitions for HN+2, 10 transitions for DN+2, and 15 transitions for DCO+. The analyses were straightforward because ground state rotational spectra are known for all three species. The resulting experimental ν3 band origins are 2257.8667(13), 2024.0141(13), and 1904.0640(20) cm−1, and the α3 (≡B″–B′) values are 329.7(12), 239.0(13), and 206.6(12) MHz for HN+2,DN+2, and DCO+, respectively.