Velocity modulation laser spectroscopy of negative ions: The infrared spectrum of hydrosulfide (SH−)

Twenty-five transitions in the v=0→1 and v=1→2 bands of 32SH−, as well as in the fundamentals of 33SH− and 34SH− have been measured with a diode laser by the velocity modulation technique. The data set was fit to an effective Hamiltonian through sextic terms to determine equilibrium molecular parameters. Comparison with the neutral SH radical shows a strong similarity in the anion and neutral molecular constants, as in the case of OH−. The agreement of experiment with ab initio calculations is found to be quite good. The rotational and vibrational temperatures of the species were estimated to be 360±50 and 960±200 K, respectively.