Structure and predissociation of the 3p;_uD³Σ _u⁺ Rydberg state of N2: First extreme-ultraviolet and new near-infrared observations, with coupled-channels analysis

The 3p;_uD³Σ_u⁺ Rydberg state of N2 is studied experimentally using two high-resolution spectroscopic techniques. First, the forbidden D ³ Σ_u⁺ -X¹ Σ_g⁺ transition is observed for the first time via the (0,0) band of ¹⁴N ₂ and the (1,0) band of ¹⁵N₂, using 1 extreme-ultraviolet +1 ultraviolet two-photon-ionization laser spectroscopy. Second, the Rydberg-Rydberg transition D ³Σ_u⁺ -E ³Σ _g⁺ is studied using near-infrared diode-laser photoabsorption spectroscopy, thus extending the previous measurements of Kanamori [J. Chem. Phys. 95, 80 (1991)], to higher transition energies, and thereby revealing the (2,2) and (3,3) bands. The combined results show that the D (v=0-3) levels exhibit rapidly increasing rotational predissociation as v increases, spanning nearly four orders of magnitude. The D -state level structure and rotational predissociation signature are explained by means of a coupled-channels model which considers the electrostatically coupled ³Π_u Rydberg-valence manifold, together with a pure-precession L -uncoupling rotational interaction between the 3p;_uD³Σ_u⁺ and 3p π _u G ³Π_u Rydberg p -complex components.