Velocity modulation infrared laser spectroscopy of negative ions: The ν3, ν3+ν1−ν1, ν3+ν2−ν2, and ν3+2ν2−2ν2 bands of cyanate (NCO−)

Abstract

We have measured 132 transitions in the ν3 (CN stretching) fundamental and the corresponding bending and stretching hotbands of the cyanate anion, ranging from P(52) to R(66), with a tunable diode laser using the velocity modulation technique. The spectra were fit to the standard linear triatomic molecule rotation–vibration Hamiltonian, yielding effective molecular parameters for the (0000), (0110), (0200), (1000), (0001), (0111), (0201), and (1001) states. The equilibrium rotational constant was determined to be B e =0.385 933(116) cm− 1. A comparison with condensed phase results is presented. As previously oberved for N− 3, cyanate is detected with high vibrational excitation in the bending mode, most likely as a consequence of the formation mechanism.