OPTICAL DOUBLE RESONANCE MULTIPHOTON IONISATION SPECTROSCOPY OF NO

Author Institution:Spectra of the 5-7s$\sigma$ states and numerous $\pi$ states of No have been obtained using optical double resonance multiphoton ionization spectroscopy. An $N_{2}$-pumped tunable dye laser is used to pump a specific rovibronic level of the $A^{2}\sum^{+} or C^{2}\pi$ states via two photon excitation. A second dye laser is tuned through resonances between the initial prepared state and higher states to generate the ionization spectrum. Due to the state selection by the pump laser, the resulting spectra are greatly simplified compared to the usual single photon spectrum. Conversely, one can set the second laser to ionize a particular rovibronic level in an upper state of interest. When scanning the excitation spectrum of this upper state with the pump laser, One then generates an ionization spectrum containing only those transitions which terminate in that particular rovibronic level. Using these two methods. One can often do rotational analyses by inspection. The results clearly illustrate the ease of analyses of complex spectra, even in the presence of large perturbations. The simplified spectra are used to study state-to-state perturbations, collisional relaxation and autoionization