Spin-orbit splittings and rotational constants for vibrationally excited levels of NCO(X2Πi)

Abstract

Laser-induced fluorescence excitation spectra at 0.3-cm−1 resolution have been–obtained for the A2Σ+–X2Πi system of NCO present in an atmospheric pressure CH4–N2O flame. This combination of selectively detected laser fluorescence and a flame environment has permitted the high-resolution investigation of levels inaccessible in conventional room temperature experiments. Spin-orbit splittings, and rotational and vibrational constants have been determined for eight vibrational levels having K = ν2 + 1, and for the 010 2Σ and the 020 2Π levels, primarily by fits to band-head positions using previously determined A2Σ+constants. The results are in good agreement with theoretical predictions of Renner–Teller interactions. Fermi resonance with an interaction strength of 10 cm−1 describes variations in spin–orbit splittings and rotational constants for four levels with ν1 = 1 quite well.