Knowledge Bank

The ground electronic state of NCS radical is a $\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}\Pi$, state and is isovalent with NCO. While NCO is one of the free radicals that have been studied very extensively in the microwave. millimeter-wave and visible-UV regions, high-resolution investigation of NCS has been relatively sparse. We studied the millimeter-wave spectrum of this radical in the ground vibrational state several year ago, and determined precise set of the molecular constants Since then we extended our measurements to the excited vibrational states, $v2=1$ state in particular. The spectrum was found to be complicated due to large Renner-Teller interaction. The $\Delta$ and $\Sigma$ Vibronic states are filed separately using effective Hamiltonians. A more complete global fit ineluding the $v2=2$ vibronic states is in progress and will be disussed.