Optical observation of the C, 3ssigma(g)F3, and 3ppi(u)G3 3Pi(u) states of N2.

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 (3)Pi(u)-X (1)Sigma(g) (+)(v,0) transitions in (14)N(2) and (15)N(2). Levels of the C (3)Pi(u) valence and 3ssigma(g)F(3) and 3ppi(u)G(3) (3)Pi(u) Rydberg states are characterized, either through their direct optical observation, or, indirectly, through their perturbative effects on the (1)Pi(u) and (1)Sigma(u) (+) states, which are accessible in dipole-allowed transitions. Optical observation of the G(3)-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 F(3)-X(0,0) transition at rotational resolution [J. P. Sprengers et al., J. Chem. Phys. 123, 144315 (2005)], the F(3)(v=1) level is found to be responsible for a local perturbation in the rotational predissociation pattern of the b(') (1)Sigma(u) (+)(v=4) state. Despite their somewhat fragmentary nature, these new observations provide a valuable database on the (3)Pi(u) states of N(2) and their interactions which will help elucidate the predissociation mechanisms for the nitrogen molecule.

Structure and predissociation of the 3psigma(u)D (3)Sigma(u) (+) Rydberg state of N(2): first extreme-ultraviolet and new near-infrared observations, with coupled-channels analysis.

The 3psigma(u)D (3)Sigma(u) (+) Rydberg state of N(2) is studied experimentally using two high-resolution spectroscopic techniques. First, the forbidden D (3)Sigma(u) (+)-X (1)Sigma(g) (+) transition is observed for the first time via the (0,0) band of (14)N(2) and the (1,0) band of (15)N(2), using 1 extreme-ultraviolet +1 ultraviolet two-photon-ionization laser spectroscopy. Second, the Rydberg-Rydberg transition D (3)Sigma(u) (+)-E (3)Sigma(g) (+) is studied using near-infrared diode-laser photoabsorption spectroscopy, thus extending the previous measurements of Kanamori et al. [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 (3)Pi(u) Rydberg-valence manifold, together with a pure-precession L-uncoupling rotational interaction between the 3psigma(u)D (3)Sigma(u) (+) and 3ppi(u)G (3)Pi(u) Rydberg p-complex components.

Optical observation of the 3s sigma gF3Pi u Rydberg state of N2.

Using ultrahigh-resolution 1 XUV+1 UV two-photon ionization laser spectroscopy, the F (3)Pi(u)<--X (1)Sigma(g) (+)(0,0) transition of N(2) has been optically observed for the first time, and the 3s sigma(g)F (3)Pi(u)(upsilon=0) Rydberg level fully characterized with rotational resolution. The experimental spectroscopic parameters and predissociation level widths suggest strong interactions between the F state and the 3p pi(u)G (3)Pi(u) Rydberg and C(') (3)Pi(u) valence states, analogous to those well known in the case of the isoconfigurational (1)Pi(u) states.

Isotopic variation of experimental lifetimes for the lowest 1 Pi u states of N2.

Lifetimes of several (1)Pi(u) states of the three natural isotopomers of molecular nitrogen, (14)N(2), (14)N(15)N, and (15)N(2), are determined via linewidth measurements in the frequency domain. Extreme ultraviolet (XUV)+UV two-photon ionization spectra of the b (1)Pi(u)(v=0-1,5-7) and c(3) (1)Pi(u)(v=0) states of (14)N(2), b (1)Pi(u)(v=0-1,5-6) and c(3) (1)Pi(u)(v=0) states of (14)N(15)N, and b (1)Pi(u)(v=0-7), c(3) (1)Pi(u)(v=0), and o (1)Pi(u)(v=0) states of (15)N(2) are recorded at ultrahigh resolution, using a narrow band tunable XUV-laser source. Lifetimes are derived from the linewidths of single rotationally resolved spectral lines after deconvolution of the instrument function. The observed lifetimes depend on the vibrational quantum number and are found to be strongly isotope dependent.

Lifetime and predissociation yield of 14N2 b 1Piu(v=1).

The lifetime of the b 1Piu(v=1) state in 14N2 has been determined experimentally using a laser-based pump-probe scheme and an exceptionally long lifetime of 2.61 ns was found. Semiempirical close-coupling calculations of the radiative lifetime, which include Rydberg-valence interactions in the singlet manifold, are consistent with this large value, giving a value of 3.61 ns and suggesting a predissociation yield of approximately 28% for this level of the b state.