Laboratory microwave spectrum and rest frequencies of the N2H+ ion

The J = 1 reverse arrow 0 multiplet of N2H+ has been detected in laboratory glow discharges in mixtures of hydrogen and nitrogen. This constitutes the first observation of this species in the laboratory by any spectroscopic method. A pattern of three lines, due to the quadrupole hyperfine splitting of the outer nitrogen, was observed, and the frequencies of these three lines were measured with the following results: F = 2 reverse arrow 1, ν = 93,173.70 +- 0.04 MHz, F = 1 reverse arrow 1, ν = 93,171.88 +- 0.04 MHz, and F = 0 reverse arrow 1, ν = 93,176.13 +- 0.22 MHz. These are in very good agreement with previous astronomical measurements