Description:
<jats:p>N(2D) can be generated by two-photon dissociation of NO above the threshold wavelength of 279 nm. A comparison of the three-photon NO+ ionization signal with the N(2D) excitation spectrum resulting from its detection by 2+1 resonance-enhanced multiphoton ionization (REMPI) shows both similarities and differences. The NO Rydberg states that are generated in the initial two-photon process either ionize or predissociate. The NO+ and N+ signals are indicative of predissociative lifetimes and channels, since an NO molecule that does not predissociate to N(2D) and O(3P) can separate to two lower atomic limits. In the 268–279 nm region there are three two-photon absorption bands, 5sσ-X 3-0, 4dπ−-X 2-0, and 5dπ−-X1-0, which show very high N(2D) predissociative yields from the upper states. A fourth band, 4dδ-X2-0, behaves in a distinctly different manner from its 4dπ− complex partner. The presence of the valence G2Σ− state, which lies within the experimental energy range, is not in evidence from either the three-photon NO+ spectrum, or from predissociation in the N(2D) channel. It appears that this state predissociates rapidly to the lower N(4S)+O(1D) or N(4S)+O(3P) limits, even above the N(2D)+O(3P) threshold.</jats:p>