Optical observation of the C, 3sσgF₃, and 3pπᵤG₃³Πᵤ states of N₂

Abstract

High-resolution laser-based one extreme-ultraviolet (EUV)+one UV two-photon ionization spectroscopy and EUV photoabsorption spectroscopy have been employed to study spin-forbidden ³Πᵤ-X ¹Σg⁺(v,0) transitions in ¹⁴N₂ and ¹⁵N₂. Levels of the C ³Πᵤ valence and 3sσgF₃ and 3pΠᵤG₃ ³Πᵤ Rydberg states are characterized, either through their direct optical observation, or, indirectly, through their perturbative effects on the ¹Πᵤ and ¹Σᵤ⁺ states, which are accessible in dipole-allowed transitions. Optical observation of the G₃-X(0,0) and (1,0) transitions is reported for the first time, together with evidence for six new vibrational levels of the C state. Following the recent observation of the F₃-X(0,0) transition at rotational resolution [J. P. Sprengers et al., J. Chem. Phys. 123, 144315 (2005)], the F₃(v=1) level is found to be responsible for a local perturbation in the rotational predissociation pattern of the b'¹Σᵤ⁺(v=4) state. Despite their somewhat fragmentary nature, these new observations provide a valuable database on the ³Πᵤ states of N₂ and their interactions which will help elucidate the predissociation mechanisms for the nitrogen molecule.