Sub-Doppler spectroscopy of the à 2Σ+-X 2Π and B 2Π-X 2Π transitions of NCO.

Sub-Doppler laser induced florescence spectra were recorded of a selection of bands within the à ²Σ⁺-X ²Π and B ²Π-X ²Π transitions of NCO in a supersonic molecular beam. The light source was a diode seeded optical parametric oscillator, which gave an effective resolution of 0.01 cm^-1 in the ultraviolet. Analysis of the à ²Σ⁺-X ²Π transition at high resolution allowed fitting of both the fine and hyperfine structures, and a set of rotational and hyperfine constants were obtained for 13 vibronic levels within the à ²Σ⁺ state including levels of both ²Σ⁺ and ²Π vibronic characters. Analysis of the 0₀⁰ and 1₀¹ bands of the B ²Π-X ²Π transition, together with a band from the à ²Σ⁺ state at the same energy, was also performed. These did not reveal any hyperfine structure although the resolution was the same as the work at lower total energy, and this observation is discussed. Refined rotational constants and perturbation parameters for the interaction between the à and B states were also obtained. [ABSTRACT FROM AUTHOR]