Extreme ultraviolet laser excitation of isotopic molecular nitrogen:: The dipole-allowed spectrum of 15N2 and 14N15N

Extreme ultraviolet+ultraviolet (XUV+UV) two-photon ionization spectra of the b (1)Pi(u)(v=0-9), c(3) (1)Pi(u)(v=0,1), o (1)Pi(u)(v=0,1), c(4)(') (1)Sigma(u)(+)(v=1) and b(') (1)Sigma(u)(+)(v=1,3-6) states of N-15(2) were recorded with a resolution of 0.3 cm(-1) full-width at half-maximum (FWHM). In addition, the b (1)Pi(u)(v=1,5-7) states of (NN)-N-14-N-15 were investigated with the same laser source. Furthermore, using an ultranarrow bandwidth XUV laser [similar to250 MHz (similar to0.01 cm(-1)) FWHM], XUV+UV ionization spectra of the b (1)Pi(u)(v=0-1,5-7), c(3) (1)Pi(u)(v=0), o (1)Pi(u)(v=0), c(4)(') (1)Sigma(u)(+)(v=0), and b(') (1)Sigma(u)(+)(v=1) states of N-15(2) were recorded in order to better resolve the band-head regions. For (NN)-N-14-N-15, ultrahigh resolution spectra of the b (1)Pi(u)(v=0-1,5-6), c(3) (1)Pi(u)(v=0), and b(') (1)Sigma(u)(+)(v=1) states were recorded. Rotational analyses were performed for each band, revealing perturbations arising from the effects of Rydberg-valence interactions in the (1)Pi(u) and (1)Sigma(u)(+) states, and rotational coupling between the (1)Pi(u) and (1)Sigma(u)(+) manifolds. Finally, a comprehensive perturbation model, based on the diabatic-potential representation used previously for N-14(2), and involving diagonalization of the full interaction matrix for all Rydberg and valence states of (1)Sigma(u)(+) and (1)Pi(u) symmetry in the energy window 100 000-110 000 cm(-1), was constructed. Term values for N-15(2) and (NN)-N-14-N-15 computed using this model were found to be in good agreement with experiment.(C) 2003 American Institute of Physics.