Microwave spectroscopy of the NCO radical in the ν2= 02Π, ν2= 12Δ, and ν2= 22Φ vibronic states

An extensive measurement of the microwave spectrum of the NCO radical has been made on the [Xtilde](0, 0, 0) 2Π i and [Xtilde](0, 1, 0) 2Δ i states, and the spectrum in the [Xtilde](0, 2, 0) 2Φ i state was also observed for the first time. From an analysis of the observed spectrum, the rotational, centrifugal distortion, spin-rotation coupling, and hyperfine coupling constants including eQq 2, the non-axially symmetric nuclear quadrupole coupling constant, were determined to good precision. The observed vibronic dependences of the hyperfine and spin-rotation coupling constants were discussed.